<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2023 Workiva-->
<!--r:042488f0-a666-455c-8991-c514440b53f2,g:8bd10ba8-749e-45a5-bb1c-c1abec558824-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:regn="http://www.regeneron.com/20221231" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2020-01-21" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.regeneron.com/20221231">
  <xs:import namespace="http://fasb.org/srt/2022" schemaLocation="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2022" schemaLocation="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd"/>
  <xs:import namespace="http://www.w3.org/1999/xlink" schemaLocation="http://www.xbrl.org/2003/xlink-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2020-01-21" schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd"/>
  <xs:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/country/2022" schemaLocation="https://xbrl.sec.gov/country/2022/country-2022.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2022" schemaLocation="https://xbrl.sec.gov/dei/2022/dei-2022.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="regn-20221231_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="regn-20221231_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="regn-20221231_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="regn-20221231_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Cover" roleURI="http://www.regeneron.com/role/Cover">
        <link:definition>0000001 - Document - Cover</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AuditInformation" roleURI="http://www.regeneron.com/role/AuditInformation">
        <link:definition>0000002 - Document - Audit Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDBALANCESHEETS" roleURI="http://www.regeneron.com/role/CONSOLIDATEDBALANCESHEETS">
        <link:definition>0000003 - Statement - CONSOLIDATED BALANCE SHEETS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDBALANCESHEETSParenthetical" roleURI="http://www.regeneron.com/role/CONSOLIDATEDBALANCESHEETSParenthetical">
        <link:definition>0000004 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVEINCOME" roleURI="http://www.regeneron.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVEINCOME">
        <link:definition>0000005 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" roleURI="http://www.regeneron.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY">
        <link:definition>0000006 - Statement - CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCASHFLOWS" roleURI="http://www.regeneron.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS">
        <link:definition>0000007 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessOverviewandSummaryofSignificantAccountingPolicies" roleURI="http://www.regeneron.com/role/BusinessOverviewandSummaryofSignificantAccountingPolicies">
        <link:definition>0000008 - Disclosure - Business Overview and Summary of Significant Accounting Policies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ProductSales" roleURI="http://www.regeneron.com/role/ProductSales">
        <link:definition>0000009 - Disclosure - Product Sales</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreements" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreements">
        <link:definition>0000010 - Disclosure - Collaboration, License, and Other Agreements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecurities" roleURI="http://www.regeneron.com/role/MarketableSecurities">
        <link:definition>0000011 - Disclosure - Marketable Securities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurements" roleURI="http://www.regeneron.com/role/FairValueMeasurements">
        <link:definition>0000012 - Disclosure - Fair Value Measurements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Inventories" roleURI="http://www.regeneron.com/role/Inventories">
        <link:definition>0000013 - Disclosure - Inventories</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PropertyPlantandEquipment" roleURI="http://www.regeneron.com/role/PropertyPlantandEquipment">
        <link:definition>0000014 - Disclosure - Property, Plant, and Equipment</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssets" roleURI="http://www.regeneron.com/role/IntangibleAssets">
        <link:definition>0000015 - Disclosure - Intangible Assets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccruedExpensesandOtherCurrentLiabilities" roleURI="http://www.regeneron.com/role/AccruedExpensesandOtherCurrentLiabilities">
        <link:definition>0000016 - Disclosure - Accrued Expenses and Other Current Liabilities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Debt" roleURI="http://www.regeneron.com/role/Debt">
        <link:definition>0000017 - Disclosure - Debt</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingencies" roleURI="http://www.regeneron.com/role/CommitmentsandContingencies">
        <link:definition>0000018 - Disclosure - Commitments and Contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquity" roleURI="http://www.regeneron.com/role/StockholdersEquity">
        <link:definition>0000019 - Disclosure - Stockholders' Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlans" roleURI="http://www.regeneron.com/role/LongTermIncentivePlans">
        <link:definition>0000020 - Disclosure - Long-Term Incentive Plans</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeSavingsPlans" roleURI="http://www.regeneron.com/role/EmployeeSavingsPlans">
        <link:definition>0000021 - Disclosure - Employee Savings Plans</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxes" roleURI="http://www.regeneron.com/role/IncomeTaxes">
        <link:definition>0000022 - Disclosure - Income Taxes</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LegalMatters" roleURI="http://www.regeneron.com/role/LegalMatters">
        <link:definition>0000023 - Disclosure - Legal Matters</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomePerShare" roleURI="http://www.regeneron.com/role/NetIncomePerShare">
        <link:definition>0000024 - Disclosure - Net Income Per Share</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StatementofCashFlows" roleURI="http://www.regeneron.com/role/StatementofCashFlows">
        <link:definition>0000025 - Disclosure - Statement of Cash Flows</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessOverviewandSummaryofSignificantAccountingPoliciesPolicies" roleURI="http://www.regeneron.com/role/BusinessOverviewandSummaryofSignificantAccountingPoliciesPolicies">
        <link:definition>0000026 - Disclosure - Business Overview and Summary of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessOverviewandSummaryofSignificantAccountingPoliciesTables" roleURI="http://www.regeneron.com/role/BusinessOverviewandSummaryofSignificantAccountingPoliciesTables">
        <link:definition>0000027 - Disclosure - Business Overview and Summary of Significant Accounting Policies (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ProductSalesTables" roleURI="http://www.regeneron.com/role/ProductSalesTables">
        <link:definition>0000028 - Disclosure - Product Sales (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsTables" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsTables">
        <link:definition>0000029 - Disclosure - Collaboration, License, and Other Agreements (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesTables" roleURI="http://www.regeneron.com/role/MarketableSecuritiesTables">
        <link:definition>0000030 - Disclosure - Marketable Securities (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsTables" roleURI="http://www.regeneron.com/role/FairValueMeasurementsTables">
        <link:definition>0000031 - Disclosure - Fair Value Measurements (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoriesTables" roleURI="http://www.regeneron.com/role/InventoriesTables">
        <link:definition>0000032 - Disclosure - Inventories (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PropertyPlantandEquipmentTables" roleURI="http://www.regeneron.com/role/PropertyPlantandEquipmentTables">
        <link:definition>0000033 - Disclosure - Property, Plant, and Equipment (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssetsTables" roleURI="http://www.regeneron.com/role/IntangibleAssetsTables">
        <link:definition>0000034 - Disclosure - Intangible Assets (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccruedExpensesandOtherCurrentLiabilitiesTables" roleURI="http://www.regeneron.com/role/AccruedExpensesandOtherCurrentLiabilitiesTables">
        <link:definition>0000035 - Disclosure - Accrued Expenses and Other Current Liabilities (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtTables" roleURI="http://www.regeneron.com/role/DebtTables">
        <link:definition>0000036 - Disclosure - Debt (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesTables" roleURI="http://www.regeneron.com/role/CommitmentsandContingenciesTables">
        <link:definition>0000037 - Disclosure - Commitments and Contingencies (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityTables" roleURI="http://www.regeneron.com/role/StockholdersEquityTables">
        <link:definition>0000038 - Disclosure - Stockholders' Equity (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlansTables" roleURI="http://www.regeneron.com/role/LongTermIncentivePlansTables">
        <link:definition>0000039 - Disclosure - Long-Term Incentive Plans (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesTables" roleURI="http://www.regeneron.com/role/IncomeTaxesTables">
        <link:definition>0000040 - Disclosure - Income Taxes (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomePerShareTables" roleURI="http://www.regeneron.com/role/NetIncomePerShareTables">
        <link:definition>0000041 - Disclosure - Net Income Per Share (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StatementofCashFlowsTables" roleURI="http://www.regeneron.com/role/StatementofCashFlowsTables">
        <link:definition>0000042 - Disclosure - Statement of Cash Flows (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessOverviewandSummaryofSignificantAccountingPoliciesNarrativeDetails" roleURI="http://www.regeneron.com/role/BusinessOverviewandSummaryofSignificantAccountingPoliciesNarrativeDetails">
        <link:definition>0000043 - Disclosure - Business Overview and Summary of Significant Accounting Policies - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessOverviewandSummaryofSignificantAccountingPoliciesScheduleofEstimatedUsefulLivesDetails" roleURI="http://www.regeneron.com/role/BusinessOverviewandSummaryofSignificantAccountingPoliciesScheduleofEstimatedUsefulLivesDetails">
        <link:definition>0000044 - Disclosure - Business Overview and Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ProductSalesScheduleofNetProductSalesDetails" roleURI="http://www.regeneron.com/role/ProductSalesScheduleofNetProductSalesDetails">
        <link:definition>0000045 - Disclosure - Product Sales - Schedule of Net Product Sales (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ProductSalesNarrativeDetails" roleURI="http://www.regeneron.com/role/ProductSalesNarrativeDetails">
        <link:definition>0000046 - Disclosure - Product Sales - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ProductSalesScheduleofConcentrationofRiskbyRiskFactorDetails" roleURI="http://www.regeneron.com/role/ProductSalesScheduleofConcentrationofRiskbyRiskFactorDetails">
        <link:definition>0000047 - Disclosure - Product Sales - Schedule of Concentration of Risk, by Risk Factor (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ProductSalesScheduleofSalesRelatedDeductionsActivityDetails" roleURI="http://www.regeneron.com/role/ProductSalesScheduleofSalesRelatedDeductionsActivityDetails">
        <link:definition>0000048 - Disclosure - Product Sales - Schedule of Sales Related Deductions Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsScheduleofCollaborationRevenueEarnedFromSanofiDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsScheduleofCollaborationRevenueEarnedFromSanofiDetails">
        <link:definition>0000049 - Disclosure - Collaboration, License, and Other Agreements - Schedule of Collaboration Revenue Earned From Sanofi (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsSanofiAntibodyNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsSanofiAntibodyNarrativeDetails">
        <link:definition>0000050 - Disclosure - Collaboration, License, and Other Agreements - Sanofi, Antibody Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsScheduleofAccountsReceivableandDeferredRevenueInformationAntibodyCollaborationDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsScheduleofAccountsReceivableandDeferredRevenueInformationAntibodyCollaborationDetails">
        <link:definition>0000051 - Disclosure - Collaboration, License, and Other Agreements - Schedule of Accounts Receivable and Deferred Revenue Information, Antibody Collaboration (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsSanofiImmunoOncologyNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsSanofiImmunoOncologyNarrativeDetails">
        <link:definition>0000052 - Disclosure - Collaboration, License, and Other Agreements - Sanofi, Immuno-Oncology Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsScheduleofAccountsReceivableandDeferredRevenueInformationIOCollaborationDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsScheduleofAccountsReceivableandDeferredRevenueInformationIOCollaborationDetails">
        <link:definition>0000053 - Disclosure - Collaboration, License, and Other Agreements - Schedule of Accounts Receivable and Deferred Revenue Information, IO Collaboration (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsBayerNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsBayerNarrativeDetails">
        <link:definition>0000054 - Disclosure - Collaboration, License, and Other Agreements - Bayer Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsScheduleofCollaborationRevenueEarnedFromBayerDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsScheduleofCollaborationRevenueEarnedFromBayerDetails">
        <link:definition>0000055 - Disclosure - Collaboration, License, and Other Agreements - Schedule of Collaboration Revenue Earned From Bayer (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsScheduleofContractBalancesBayerCollaborativeDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsScheduleofContractBalancesBayerCollaborativeDetails">
        <link:definition>0000056 - Disclosure - Collaboration, License, and Other Agreements - Schedule of Contract Balances, Bayer Collaborative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsIntelliaNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsIntelliaNarrativeDetails">
        <link:definition>0000057 - Disclosure - Collaboration, License, and Other Agreements - Intellia Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsUSGovernmentNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsUSGovernmentNarrativeDetails">
        <link:definition>0000058 - Disclosure - Collaboration, License, and Other Agreements - U.S. Government Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsAmountsRecognizedinStatementofOperationswithRocheDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsAmountsRecognizedinStatementofOperationswithRocheDetails">
        <link:definition>0000059 - Disclosure - Collaboration, License, and Other Agreements - Amounts Recognized in Statement of Operations with Roche (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsScheduleofContractBalancesRocheCollaborationDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsScheduleofContractBalancesRocheCollaborationDetails">
        <link:definition>0000060 - Disclosure - Collaboration, License, and Other Agreements - Schedule of Contract Balances, Roche Collaboration (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsAlnylamNarrativesDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsAlnylamNarrativesDetails">
        <link:definition>0000061 - Disclosure - Collaboration, License, and Other Agreements - Alnylam Narratives (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsCheckmateNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsCheckmateNarrativeDetails">
        <link:definition>0000062 - Disclosure - Collaboration, License, and Other Agreements - Checkmate Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsTevaNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsTevaNarrativeDetails">
        <link:definition>0000063 - Disclosure - Collaboration, License, and Other Agreements - Teva Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsAmountsRecognizedinStatementofOperationswithTevaDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsAmountsRecognizedinStatementofOperationswithTevaDetails">
        <link:definition>0000064 - Disclosure - Collaboration, License, and Other Agreements - Amounts Recognized in Statement of Operations with Teva (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborationLicenseandOtherAgreementsScheduleofContractBalancesTevaCollaborationDetails" roleURI="http://www.regeneron.com/role/CollaborationLicenseandOtherAgreementsScheduleofContractBalancesTevaCollaborationDetails">
        <link:definition>0000065 - Disclosure - Collaboration, License, and Other Agreements - Schedule of Contract Balances, Teva Collaboration (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesScheduleofInvestmentsinAvailableForSaleDebtSecuritiesDetails" roleURI="http://www.regeneron.com/role/MarketableSecuritiesScheduleofInvestmentsinAvailableForSaleDebtSecuritiesDetails">
        <link:definition>0000066 - Disclosure - Marketable Securities - Schedule of Investments in Available For Sale Debt Securities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesScheduleofDebtSecuritiesBasedonContractualMaturityDatesDetails" roleURI="http://www.regeneron.com/role/MarketableSecuritiesScheduleofDebtSecuritiesBasedonContractualMaturityDatesDetails">
        <link:definition>0000067 - Disclosure - Marketable Securities - Schedule of Debt Securities Based on Contractual Maturity Dates (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesScheduleofFairValueandUnrealizedLossesofDebtSecuritiesDetails" roleURI="http://www.regeneron.com/role/MarketableSecuritiesScheduleofFairValueandUnrealizedLossesofDebtSecuritiesDetails">
        <link:definition>0000068 - Disclosure - Marketable Securities - Schedule of Fair Value and Unrealized Losses of Debt Securities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesNarrativeDetails" roleURI="http://www.regeneron.com/role/MarketableSecuritiesNarrativeDetails">
        <link:definition>0000069 - Disclosure - Marketable Securities - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsScheduleofAssetsMeasuredatFairValueonaRecurringBasisDetails" roleURI="http://www.regeneron.com/role/FairValueMeasurementsScheduleofAssetsMeasuredatFairValueonaRecurringBasisDetails">
        <link:definition>0000070 - Disclosure - Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsNarrativeDetails" roleURI="http://www.regeneron.com/role/FairValueMeasurementsNarrativeDetails">
        <link:definition>0000071 - Disclosure - Fair Value Measurements - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoriesScheduleofInventoriesDetails" roleURI="http://www.regeneron.com/role/InventoriesScheduleofInventoriesDetails">
        <link:definition>0000072 - Disclosure - Inventories - Schedule of Inventories (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoriesNarrativeDetails" roleURI="http://www.regeneron.com/role/InventoriesNarrativeDetails">
        <link:definition>0000073 - Disclosure - Inventories - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" roleURI="http://www.regeneron.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails">
        <link:definition>0000074 - Disclosure - Property, Plant, and Equipment - Schedule of Property, Plant, and Equipment (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PropertyPlantandEquipmentNarrativeDetails" roleURI="http://www.regeneron.com/role/PropertyPlantandEquipmentNarrativeDetails">
        <link:definition>0000075 - Disclosure - Property, Plant, and Equipment - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssetsScheduleofIntangibleAssetsDetails" roleURI="http://www.regeneron.com/role/IntangibleAssetsScheduleofIntangibleAssetsDetails">
        <link:definition>0000076 - Disclosure - Intangible Assets - Schedule of Intangible Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssetsNarrativeDetails" roleURI="http://www.regeneron.com/role/IntangibleAssetsNarrativeDetails">
        <link:definition>0000077 - Disclosure - Intangible Assets - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccruedExpensesandOtherCurrentLiabilitiesScheduleofAccruedExpensesandOtherCurrentLiabilitiesDetails" roleURI="http://www.regeneron.com/role/AccruedExpensesandOtherCurrentLiabilitiesScheduleofAccruedExpensesandOtherCurrentLiabilitiesDetails">
        <link:definition>0000078 - Disclosure - Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtNarrativeDetails" roleURI="http://www.regeneron.com/role/DebtNarrativeDetails">
        <link:definition>0000079 - Disclosure - Debt - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtSummaryofIssuedSeniorUnsecuredNotesDetails" roleURI="http://www.regeneron.com/role/DebtSummaryofIssuedSeniorUnsecuredNotesDetails">
        <link:definition>0000080 - Disclosure - Debt - Summary of Issued Senior Unsecured Notes (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesLeasesnarrativeDetails" roleURI="http://www.regeneron.com/role/CommitmentsandContingenciesLeasesnarrativeDetails">
        <link:definition>0000081 - Disclosure - Commitments and Contingencies - Leases narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesAmountsrecognizedinCondensedConsolidatedBalanceSheetDetails" roleURI="http://www.regeneron.com/role/CommitmentsandContingenciesAmountsrecognizedinCondensedConsolidatedBalanceSheetDetails">
        <link:definition>0000082 - Disclosure - Commitments and Contingencies - Amounts recognized in Condensed Consolidated Balance Sheet (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesFinanceleasecostsDetails" roleURI="http://www.regeneron.com/role/CommitmentsandContingenciesFinanceleasecostsDetails">
        <link:definition>0000083 - Disclosure - Commitments and Contingencies - Finance lease costs (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesOtherinformationrelatedtofinanceleaseDetails" roleURI="http://www.regeneron.com/role/CommitmentsandContingenciesOtherinformationrelatedtofinanceleaseDetails">
        <link:definition>0000084 - Disclosure - Commitments and Contingencies - Other information related to finance lease (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesAnalysisofleaseliabilitymaturitiesDetails" roleURI="http://www.regeneron.com/role/CommitmentsandContingenciesAnalysisofleaseliabilitymaturitiesDetails">
        <link:definition>0000085 - Disclosure - Commitments and Contingencies - Analysis of lease liability maturities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesAnalysisofleaseliabilitymaturitiesDetails_1" roleURI="http://www.regeneron.com/role/CommitmentsandContingenciesAnalysisofleaseliabilitymaturitiesDetails_1">
        <link:definition>0000085 - Disclosure - Commitments and Contingencies - Analysis of lease liability maturities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesResearchCollaborationandLicensingAgreementsNarrativeDetails" roleURI="http://www.regeneron.com/role/CommitmentsandContingenciesResearchCollaborationandLicensingAgreementsNarrativeDetails">
        <link:definition>0000086 - Disclosure - Commitments and Contingencies - Research Collaboration and Licensing Agreements Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityNarrativeDetails" roleURI="http://www.regeneron.com/role/StockholdersEquityNarrativeDetails">
        <link:definition>0000087 - Disclosure - Stockholders' Equity - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityScheduleofRepurchasedSharesDetails" roleURI="http://www.regeneron.com/role/StockholdersEquityScheduleofRepurchasedSharesDetails">
        <link:definition>0000088 - Disclosure - Stockholders' Equity - Schedule of Repurchased Shares (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlansNarrativeDetails" roleURI="http://www.regeneron.com/role/LongTermIncentivePlansNarrativeDetails">
        <link:definition>0000089 - Disclosure - Long-Term Incentive Plans - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlansSummaryoftransactionsinvolvingstockoptionawardsDetails" roleURI="http://www.regeneron.com/role/LongTermIncentivePlansSummaryoftransactionsinvolvingstockoptionawardsDetails">
        <link:definition>0000090 - Disclosure - Long-Term Incentive Plans - Summary of transactions involving stock option awards (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlansSummaryofweightedaverageexercisepricesandweightedaveragegrantdatefairvaluesofoptionsissuedDetails" roleURI="http://www.regeneron.com/role/LongTermIncentivePlansSummaryofweightedaverageexercisepricesandweightedaveragegrantdatefairvaluesofoptionsissuedDetails">
        <link:definition>0000091 - Disclosure - Long-Term Incentive Plans - Summary of weighted-average exercise prices and weighted-average grant-date fair values of options issued (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlansSummaryofweightedaveragevaluesofassumptionsusedincomputingfairvalueofoptiongrantsDetails" roleURI="http://www.regeneron.com/role/LongTermIncentivePlansSummaryofweightedaveragevaluesofassumptionsusedincomputingfairvalueofoptiongrantsDetails">
        <link:definition>0000092 - Disclosure - Long-Term Incentive Plans - Summary of weighted-average values of assumptions used in computing fair value of option grants (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlansSummaryofactivityrelatedtorestrictedstockawardsDetails" roleURI="http://www.regeneron.com/role/LongTermIncentivePlansSummaryofactivityrelatedtorestrictedstockawardsDetails">
        <link:definition>0000093 - Disclosure - Long-Term Incentive Plans - Summary of activity related to restricted stock awards (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlansSummaryofactivityrelatedtoperformancebasedawardsDetails" roleURI="http://www.regeneron.com/role/LongTermIncentivePlansSummaryofactivityrelatedtoperformancebasedawardsDetails">
        <link:definition>0000094 - Disclosure - Long-Term Incentive Plans - Summary of activity related to performance-based awards (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LongTermIncentivePlansSummaryofweightedaveragevaluesofassumptionsusedincomputingfairvalueofperformancebasedoptionsDetails" roleURI="http://www.regeneron.com/role/LongTermIncentivePlansSummaryofweightedaveragevaluesofassumptionsusedincomputingfairvalueofperformancebasedoptionsDetails">
        <link:definition>0000095 - Disclosure - Long-Term Incentive Plans - Summary of weighted-average values of assumptions used in computing fair value of performance-based options (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeSavingsPlansDetails" roleURI="http://www.regeneron.com/role/EmployeeSavingsPlansDetails">
        <link:definition>0000096 - Disclosure - Employee Savings Plans (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofincomebeforeincometaxDetails" roleURI="http://www.regeneron.com/role/IncomeTaxesScheduleofincomebeforeincometaxDetails">
        <link:definition>0000097 - Disclosure - Income Taxes - Schedule of income before income tax (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofcomponentsofincometaxexpenseDetails" roleURI="http://www.regeneron.com/role/IncomeTaxesScheduleofcomponentsofincometaxexpenseDetails">
        <link:definition>0000098 - Disclosure - Income Taxes - Schedule of components of income tax expense (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofeffectiveincometaxratereconciliationDetails" roleURI="http://www.regeneron.com/role/IncomeTaxesScheduleofeffectiveincometaxratereconciliationDetails">
        <link:definition>0000099 - Disclosure - Income Taxes - Schedule of effective income tax rate reconciliation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofdeferredtaxassetsandliabilitiesDetails" roleURI="http://www.regeneron.com/role/IncomeTaxesScheduleofdeferredtaxassetsandliabilitiesDetails">
        <link:definition>0000100 - Disclosure - Income Taxes - Schedule of deferred tax assets and liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesNarrativeDetails" roleURI="http://www.regeneron.com/role/IncomeTaxesNarrativeDetails">
        <link:definition>0000101 - Disclosure - Income Taxes - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofunrecognizedtaxbenefitsDetails" roleURI="http://www.regeneron.com/role/IncomeTaxesScheduleofunrecognizedtaxbenefitsDetails">
        <link:definition>0000102 - Disclosure - Income Taxes - Schedule of unrecognized tax benefits (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LegalMattersDetails" roleURI="http://www.regeneron.com/role/LegalMattersDetails">
        <link:definition>0000103 - Disclosure - Legal Matters (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomePerShareScheduleofBasicandDilutedNetIncomePerShareDetails" roleURI="http://www.regeneron.com/role/NetIncomePerShareScheduleofBasicandDilutedNetIncomePerShareDetails">
        <link:definition>0000104 - Disclosure - Net Income Per Share - Schedule of Basic and Diluted Net Income Per Share (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomePerShareScheduleofAntidilutiveSecuritiesExcludedFromComputationDetails" roleURI="http://www.regeneron.com/role/NetIncomePerShareScheduleofAntidilutiveSecuritiesExcludedFromComputationDetails">
        <link:definition>0000105 - Disclosure - Net Income Per Share - Schedule of Antidilutive Securities Excluded From Computation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StatementofCashFlowsScheduleofReconciliationofCashCashEquivalentsandRestrictedCashDetails" roleURI="http://www.regeneron.com/role/StatementofCashFlowsScheduleofReconciliationofCashCashEquivalentsandRestrictedCashDetails">
        <link:definition>0000106 - Disclosure - Statement of Cash Flows - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StatementofCashFlowsSummaryofNonCashInvestingandFinancingActivitiesDetails" roleURI="http://www.regeneron.com/role/StatementofCashFlowsSummaryofNonCashInvestingandFinancingActivitiesDetails">
        <link:definition>0000107 - Disclosure - Statement of Cash Flows - Summary of Non-Cash Investing and Financing Activities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="regn_ShareOfLossesOutsideUnitedStatesForCollaboratingParty" abstract="false" name="ShareOfLossesOutsideUnitedStatesForCollaboratingParty" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_ContingentReimbursementObligation" abstract="false" name="ContingentReimbursementObligation" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LaboratoryAndOfficeFacilitiesMember" abstract="true" name="LaboratoryAndOfficeFacilitiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SanofiMember" abstract="true" name="SanofiMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_AssetsAndLiabilitiesLesseeTableTextBlock" abstract="false" name="AssetsAndLiabilitiesLesseeTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="regn_SanofisShareOfLibtayoUSGrossProfitsMember" abstract="true" name="SanofisShareOfLibtayoUSGrossProfitsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_AccrualForSalesRelatedCostsCurrent" abstract="false" name="AccrualForSalesRelatedCostsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" abstract="true" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_DistributionRelatedFeesMember" abstract="true" name="DistributionRelatedFeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_EYLEAAfliberceptInjectionMember" abstract="true" name="EYLEAAfliberceptInjectionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ArcalystNetProductSalesMember" abstract="true" name="ArcalystNetProductSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_LossContingencyExParteReexaminationFiledNumber" abstract="false" name="LossContingencyExParteReexaminationFiledNumber" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_LongTermIncentivePlan2000Member" abstract="true" name="LongTermIncentivePlan2000Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_PaymentsMadeToAcquireEquityWithinACollaborationAgreement" abstract="false" name="PaymentsMadeToAcquireEquityWithinACollaborationAgreement" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramNovember2021Member" abstract="true" name="ShareRepurchaseProgramNovember2021Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ClassificationOfInvestmentDomain" abstract="true" name="ClassificationOfInvestmentDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SanofiCollaborationAgreementImmunooncologyMember" abstract="true" name="SanofiCollaborationAgreementImmunooncologyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_DeferredTaxAssetsCapitalizedResearchAndDevelopmentExpenses" abstract="false" name="DeferredTaxAssetsCapitalizedResearchAndDevelopmentExpenses" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_BARDAOtherTransactionAgreementMember" abstract="true" name="BARDAOtherTransactionAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_AlnylamPharmaceuticalsInc.StockPurchaseAgreementMember" abstract="true" name="AlnylamPharmaceuticalsInc.StockPurchaseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_InmazebMember" abstract="true" name="InmazebMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_PaymentToCollaboratingParty" abstract="false" name="PaymentToCollaboratingParty" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" abstract="false" name="PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="regn_RonapreveMember" abstract="true" name="RonapreveMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RoyaltyRateMinimum" abstract="false" name="RoyaltyRateMinimum" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_A338PatentAnd069PatentMember" abstract="true" name="A338PatentAnd069PatentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SanofiCollaborationAgreementAntibodyMember" abstract="true" name="SanofiCollaborationAgreementAntibodyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_PercentageOfShareOfProfitsUsedToReimburseCollaboratingPartyForTrialCosts" abstract="false" name="PercentageOfShareOfProfitsUsedToReimburseCollaboratingPartyForTrialCosts" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_January12024ThroughDecember312026Member" abstract="true" name="January12024ThroughDecember312026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_AcquiredInProcessResearchAndDevelopment" abstract="false" name="AcquiredInProcessResearchAndDevelopment" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ThreeIndividualCustomersMember" abstract="true" name="ThreeIndividualCustomersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_AmendedRestatedLongTermIncentivePlan2014Member" abstract="true" name="AmendedRestatedLongTermIncentivePlan2014Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ExtensionOfResearchTermFee" abstract="false" name="ExtensionOfResearchTermFee" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_RoyaltyRateMaximum" abstract="false" name="RoyaltyRateMaximum" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_StockIssuedDistributedDuringPeriodValueEmployeeBenefitPlan" abstract="false" name="StockIssuedDistributedDuringPeriodValueEmployeeBenefitPlan" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_CheckmatePharmaceuticalsIncMember" abstract="true" name="CheckmatePharmaceuticalsIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_UpFrontPaymentReceived" abstract="false" name="UpFrontPaymentReceived" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" abstract="false" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_RestrictedMember" abstract="true" name="RestrictedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_AggregateSalesBasedMilestoneMember" abstract="true" name="AggregateSalesBasedMilestoneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesMilestonesAxis" abstract="true" name="SalesMilestonesAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_PercentageOfQuarterlyProfitsRequiredToBePaidForReimbursementOfDevelopmentCosts" abstract="false" name="PercentageOfQuarterlyProfitsRequiredToBePaidForReimbursementOfDevelopmentCosts" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_NumberOfProductsApprovedByTheUnitesStatesFoodAndDrugAdministration" abstract="false" name="NumberOfProductsApprovedByTheUnitesStatesFoodAndDrugAdministration" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_MaximumPercentageOfOutstandingSharesThatMayBeAcquiredUnderStandstillProvisions" abstract="false" name="MaximumPercentageOfOutstandingSharesThatMayBeAcquiredUnderStandstillProvisions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_ApotexIncMember" abstract="true" name="ApotexIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_FurnitureOfficeEquipmentAndOtherMember" abstract="true" name="FurnitureOfficeEquipmentAndOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_MaximumAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels" abstract="false" name="MaximumAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_BayerCollaborationAgreementMember" abstract="true" name="BayerCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RoyaltyPaymentToCollaboratingPartyPercentageOfNetProductSales" abstract="false" name="RoyaltyPaymentToCollaboratingPartyPercentageOfNetProductSales" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_RegulatoryMilestoneMember" abstract="true" name="RegulatoryMilestoneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_TevaPharmaceuticalsCollaborationAgreementMember" abstract="true" name="TevaPharmaceuticalsCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ReimbursementOfCommercializationRelatedExpensesMember" abstract="true" name="ReimbursementOfCommercializationRelatedExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_CelltrionIncMember" abstract="true" name="CelltrionIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_OtherCollaborationAgreementsMember" abstract="true" name="OtherCollaborationAgreementsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_A631PatentMember" abstract="true" name="A631PatentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RevenueBasedOnPercentageOfAnnualSalesInJapan" abstract="false" name="RevenueBasedOnPercentageOfAnnualSalesInJapan" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_FinanceLeaseRemainingLeaseTerm" abstract="false" name="FinanceLeaseRemainingLeaseTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" abstract="false" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_CollaborativeArrangementNumberOfDosesCounterpartyToPurchase" abstract="false" name="CollaborativeArrangementNumberOfDosesCounterpartyToPurchase" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_ClassificationOfInvestmentAxis" abstract="true" name="ClassificationOfInvestmentAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" abstract="false" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_OptionToExtendResearchTermPeriod" abstract="false" name="OptionToExtendResearchTermPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="regn_USGovernmentMember" abstract="true" name="USGovernmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RocheCollaborationAgreementMember" abstract="true" name="RocheCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_PaymentsForRoyaltiesPercentage" abstract="false" name="PaymentsForRoyaltiesPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_DebtSecuritiesAvailableForSaleFairValueMaturityAllocatedAndSingleMaturityDateAfterYear5" abstract="false" name="DebtSecuritiesAvailableForSaleFairValueMaturityAllocatedAndSingleMaturityDateAfterYear5" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="regn_ResearchCollaborationAndLicensingArrangementsTable" abstract="true" name="ResearchCollaborationAndLicensingArrangementsTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_PaymentsToAcquireIntangibleAssets1" abstract="false" name="PaymentsToAcquireIntangibleAssets1" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_AmendedIODiscoveryAgreementMember" abstract="true" name="AmendedIODiscoveryAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_FinanceLeaseCost" abstract="false" name="FinanceLeaseCost" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_PercentageOfRoyaltyPaymentThatCanBeOffset" abstract="false" name="PercentageOfRoyaltyPaymentThatCanBeOffset" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_PraluentCrossLicenseAndCommercializationAgreementMember" abstract="true" name="PraluentCrossLicenseAndCommercializationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ResearchCollaborationAndLicensingAgreementsAxis" abstract="true" name="ResearchCollaborationAndLicensingAgreementsAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_ThroughDecember312023Member" abstract="true" name="ThroughDecember312023Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_InitialResearchTerm" abstract="false" name="InitialResearchTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="regn_AccruedClinicalTrialExpenseCurrent" abstract="false" name="AccruedClinicalTrialExpenseCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_PotentialExtensionOfResearchTerm" abstract="false" name="PotentialExtensionOfResearchTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="regn_ShareOfLossesOutsideUnitedStatesForCompany" abstract="false" name="ShareOfLossesOutsideUnitedStatesForCompany" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_EffectiveIncomeTaxRateReconciliationSaleOfNonInventoryRelatedAssetsBetweenForeignSubsidiariesPercent" abstract="false" name="EffectiveIncomeTaxRateReconciliationSaleOfNonInventoryRelatedAssetsBetweenForeignSubsidiariesPercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_CollaborativeArrangementAdditionalPaymentEligibleMilestone" abstract="false" name="CollaborativeArrangementAdditionalPaymentEligibleMilestone" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_PaymentsForAssetAcquisition" abstract="false" name="PaymentsForAssetAcquisition" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_IntelliaCollaborationAgreementMember" abstract="true" name="IntelliaCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_NonPerformanceBasedStockOptionsMember" abstract="true" name="NonPerformanceBasedStockOptionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_MarketableAndOtherSecuritiesGainLoss" abstract="false" name="MarketableAndOtherSecuritiesGainLoss" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ReimbursementOfResearchAndDevelopmentExpensesNetOfObligationForShareOfRDExpensesMember" abstract="true" name="ReimbursementOfResearchAndDevelopmentExpensesNetOfObligationForShareOfRDExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_OtherSalesRelatedDeductionsMember" abstract="true" name="OtherSalesRelatedDeductionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SanofiCollaborationRevenueMember" abstract="true" name="SanofiCollaborationRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ReimbursementOfResearchAndDevelopmentExpensesMember" abstract="true" name="ReimbursementOfResearchAndDevelopmentExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_PercentageOfRepaymentOfDevelopmentBalanceOutOfProfits" abstract="false" name="PercentageOfRepaymentOfDevelopmentBalanceOutOfProfits" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_ResearchCollaborationAndLicensingArrangementsLineItems" abstract="true" name="ResearchCollaborationAndLicensingArrangementsLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="regn_AmountsRecognizedInConnectionWithUpFrontPaymentsMember" abstract="true" name="AmountsRecognizedInConnectionWithUpFrontPaymentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" abstract="false" name="EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_ComputerEquipmentAndSoftwareMember" abstract="true" name="ComputerEquipmentAndSoftwareMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_CollaborativeArrangementUpfrontPaymentMade" abstract="false" name="CollaborativeArrangementUpfrontPaymentMade" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_A226PatentAnd992PatentMember" abstract="true" name="A226PatentAnd992PatentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_AlnylamPharmaceuticalsInc.CollaborationAgreementMember" abstract="true" name="AlnylamPharmaceuticalsInc.CollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramsMember" abstract="true" name="ShareRepurchaseProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" abstract="false" name="ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="regn_CollaborativeAgreementsObligationsCurrent" abstract="false" name="CollaborativeAgreementsObligationsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ResearchCollaborationAndLicensingAgreementsDomain" abstract="true" name="ResearchCollaborationAndLicensingAgreementsDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ProductRightsMember" abstract="true" name="ProductRightsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesBasedMilestoneOneMember" abstract="true" name="SalesBasedMilestoneOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_UnrecognizedTaxBenefitsDecreaseResultingFromSettlementsWithTaxingAuthoritiesAndReductionResultingFromLapseOfApplicableStatuteOfLimitations" abstract="false" name="UnrecognizedTaxBenefitsDecreaseResultingFromSettlementsWithTaxingAuthoritiesAndReductionResultingFromLapseOfApplicableStatuteOfLimitations" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_SalesBasedMilestoneTwoMember" abstract="true" name="SalesBasedMilestoneTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_StockIssuedDistributedDuringPeriodSharesEmployeeBenefitPlan" abstract="false" name="StockIssuedDistributedDuringPeriodSharesEmployeeBenefitPlan" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="regn_LibtayoDevelopmentAndDupilumabItepekimabEligibleInvestmentsMember" abstract="true" name="LibtayoDevelopmentAndDupilumabItepekimabEligibleInvestmentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RegeneronsShareOfResearchAndDevelopmentExpensesMember" abstract="true" name="RegeneronsShareOfResearchAndDevelopmentExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_DebtInstrumentRedemptionPriceWithChangeInControlProvisionPercentage" abstract="false" name="DebtInstrumentRedemptionPriceWithChangeInControlProvisionPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_RestOfWorldMember" abstract="true" name="RestOfWorldMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RegeneronsShareOfCommercialExpensesMember" abstract="true" name="RegeneronsShareOfCommercialExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_McKessonCorporationMember" abstract="true" name="McKessonCorporationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_DepreciationDepletionAndAmortizationExcludingIntangibleAssets" abstract="false" name="DepreciationDepletionAndAmortizationExcludingIntangibleAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_PraluentNetProductSalesMember" abstract="true" name="PraluentNetProductSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_UpfrontPaymentMade" abstract="false" name="UpfrontPaymentMade" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_GrossProductRevenueMember" abstract="true" name="GrossProductRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ShareOfProfitsLossesInConnectionWithCommercializationMember" abstract="true" name="ShareOfProfitsLossesInConnectionWithCommercializationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesMilestoneThreeMember" abstract="true" name="SalesMilestoneThreeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SanofiCollaborationAgreementAmendedAndRestatedImmunoOncologyLicenseAndCollaborationAgreementMember" abstract="true" name="SanofiCollaborationAgreementAmendedAndRestatedImmunoOncologyLicenseAndCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_CollaborationRevenueMember" abstract="true" name="CollaborationRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesMilestoneOneMember" abstract="true" name="SalesMilestoneOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_LossContingencyPercentageOfDamagesResponsibleFor" abstract="false" name="LossContingencyPercentageOfDamagesResponsibleFor" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_MaximumTransactionAgreementPayments" abstract="false" name="MaximumTransactionAgreementPayments" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" abstract="false" name="EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_SalesMilestoneFourMember" abstract="true" name="SalesMilestoneFourMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_NetProfitInConnectionWithCommercializationMember" abstract="true" name="NetProfitInConnectionWithCommercializationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_LIBTAYONetProductSalesMember" abstract="true" name="LIBTAYONetProductSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesMilestoneTwoMember" abstract="true" name="SalesMilestoneTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramJanuary2023Member" abstract="true" name="ShareRepurchaseProgramJanuary2023Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_IOLicenseandCollaborationAgreementMember" abstract="true" name="IOLicenseandCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_UnrestrictedMember" abstract="true" name="UnrestrictedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_OneTimePaymentInConnectionWithChangeInJapanArrangementMember" abstract="true" name="OneTimePaymentInConnectionWithChangeInJapanArrangementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_EffectiveIncomeTaxRateReconciliationDeductionForeignIntangibleIncomePercent" abstract="false" name="EffectiveIncomeTaxRateReconciliationDeductionForeignIntangibleIncomePercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_EvkeezaMember" abstract="true" name="EvkeezaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SeniorUnsecuredNotesDue2050Member" abstract="true" name="SeniorUnsecuredNotesDue2050Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_NumberOfVotesPerShare" abstract="false" name="NumberOfVotesPerShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_PercentageOfTrialCostsRequiredToBeFundedByCollaboratingParty" abstract="false" name="PercentageOfTrialCostsRequiredToBeFundedByCollaboratingParty" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_REGENCOVMember" abstract="true" name="REGENCOVMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesMilestoneFiveMember" abstract="true" name="SalesMilestoneFiveMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesMilestonesDomain" abstract="true" name="SalesMilestonesDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_UpFrontPaymentToCollaboratingParty" abstract="false" name="UpFrontPaymentToCollaboratingParty" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LongTermIncentivePlan2014Member" abstract="true" name="LongTermIncentivePlan2014Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_CostOfGoodsSoldMember" abstract="true" name="CostOfGoodsSoldMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RevenueRemainingPerformanceObligationVariableConsiderationAmount" abstract="false" name="RevenueRemainingPerformanceObligationVariableConsiderationAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ReimbursementForManufacturingOfCommercialSuppliesMember" abstract="true" name="ReimbursementForManufacturingOfCommercialSuppliesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_CollaborationandContractManufacturingMember" abstract="true" name="CollaborationandContractManufacturingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SeniorUnsecuredNotesDue2030Member" abstract="true" name="SeniorUnsecuredNotesDue2030Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_AuditInformationAbstract" abstract="true" name="AuditInformationAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="regn_LineOfCreditFacilityIncreaseLimit" abstract="false" name="LineOfCreditFacilityIncreaseLimit" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramJanuary2021Member" abstract="true" name="ShareRepurchaseProgramJanuary2021Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RebatesAndChargebacksMember" abstract="true" name="RebatesAndChargebacksMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesBasedMilestoneEarnedMember" abstract="true" name="SalesBasedMilestoneEarnedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ShareRepurchaseProgram2019Member" abstract="true" name="ShareRepurchaseProgram2019Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_RoyaltyPercentageToBeReceivedOnNetProductSalesOutsideOfUnitedStates" abstract="false" name="RoyaltyPercentageToBeReceivedOnNetProductSalesOutsideOfUnitedStates" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="regn_BesseMedicalMember" abstract="true" name="BesseMedicalMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_NumberOfInterPartiesReviewIPRPetitionsFiled" abstract="false" name="NumberOfInterPartiesReviewIPRPetitionsFiled" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" abstract="true" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_EyleaNetProductSalesMember" abstract="true" name="EyleaNetProductSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
