<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<xsd:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.regeneron.com/20200331" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric" xmlns:num="http://www.xbrl.org/dtr/type/numeric" xmlns:regn="http://www.regeneron.com/20200331" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xsd:import namespace="http://fasb.org/srt-types/2019-01-31" schemaLocation="http://xbrl.fasb.org/srt/2019/elts/srt-types-2019-01-31.xsd" />
  <xsd:import namespace="http://fasb.org/srt/2019-01-31" schemaLocation="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd" />
  <xsd:import namespace="http://fasb.org/us-gaap/2019-01-31" schemaLocation="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd" />
  <xsd:import namespace="http://fasb.org/us-roles/2019-01-31" schemaLocation="http://xbrl.fasb.org/us-gaap/2019/elts/us-roles-2019-01-31.xsd" />
  <xsd:import namespace="http://fasb.org/us-types/2019-01-31" schemaLocation="http://xbrl.fasb.org/us-gaap/2019/elts/us-types-2019-01-31.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2009/arcrole/fact-explanatoryFact" schemaLocation="http://www.xbrl.org/lrr/arcrole/factExplanatory-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2009/role/negated" schemaLocation="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2009/role/net" schemaLocation="http://www.xbrl.org/lrr/role/net-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/dtr/type/non-numeric" schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/dtr/type/numeric" schemaLocation="http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd" />
  <xsd:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/country/2017-01-31" schemaLocation="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/currency/2019-01-31" schemaLocation="https://xbrl.sec.gov/currency/2019/currency-2019-01-31.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/dei/2019-01-31" schemaLocation="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/exch/2019-01-31" schemaLocation="https://xbrl.sec.gov/exch/2019/exch-2019-01-31.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/naics/2017-01-31" schemaLocation="http://xbrl.sec.gov/naics/2017/naics-2017-01-31.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/sic/2011-01-31" schemaLocation="http://xbrl.sec.gov/sic/2011/sic-2011-01-31.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/stpr/2018-01-31" schemaLocation="https://xbrl.sec.gov/stpr/2018/stpr-2018-01-31.xsd" />
  <xsd:annotation>
    <xsd:appinfo>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="regn-20200331_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="regn-20200331_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="regn-20200331_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="regn-20200331_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple" />
      <link:roleType id="CollaborationAgreements" roleURI="http://www.regeneron.com/role/CollaborationAgreements">
        <link:definition>2104100 - Disclosure - Collaboration 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="CollaborationAgreementsAmountsRecognizedInStatementOfOperationsWithBayerDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsAmountsRecognizedInStatementOfOperationsWithBayerDetails">
        <link:definition>2404409 - Disclosure - Collaboration Agreements - Amounts Recognized in Statement of Operations with 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="CollaborationAgreementsAmountsRecognizedInStatementOfOperationsWithSanofiDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsAmountsRecognizedInStatementOfOperationsWithSanofiDetails">
        <link:definition>2404402 - Disclosure - Collaboration Agreements - Amounts Recognized In Statement of Operations with 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="CollaborationAgreementsAmountsRecognizedInStatementOfOperationsWithTevaDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsAmountsRecognizedInStatementOfOperationsWithTevaDetails">
        <link:definition>2404413 - Disclosure - Collaboration 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="CollaborationAgreementsBayerNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsBayerNarrativeDetails">
        <link:definition>2404410 - Disclosure - Collaboration 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="CollaborationAgreementsSanofiAntibodyNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsSanofiAntibodyNarrativeDetails">
        <link:definition>2404403 - Disclosure - Collaboration 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="CollaborationAgreementsSanofiImmunoOncologyNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsSanofiImmunoOncologyNarrativeDetails">
        <link:definition>2404406 - Disclosure - Collaboration 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="CollaborationAgreementsScheduleOfContractBalancesAntibodyCollaborationDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsScheduleOfContractBalancesAntibodyCollaborationDetails">
        <link:definition>2404404 - Disclosure - Collaboration Agreements - Schedule of Contract Balances, 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="CollaborationAgreementsScheduleOfContractBalancesBayerCollaborationDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsScheduleOfContractBalancesBayerCollaborationDetails">
        <link:definition>2404411 - Disclosure - Collaboration Agreements - Schedule of Contract Balances, Bayer 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="CollaborationAgreementsScheduleOfContractBalancesIoCollaborationDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsScheduleOfContractBalancesIoCollaborationDetails">
        <link:definition>2404407 - Disclosure - Collaboration Agreements - Schedule of Contract Balances, 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="CollaborationAgreementsScheduleOfContractBalancesTevaCollaborationDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsScheduleOfContractBalancesTevaCollaborationDetails">
        <link:definition>2404414 - Disclosure - Collaboration 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="CollaborationAgreementsTables" roleURI="http://www.regeneron.com/role/CollaborationAgreementsTables">
        <link:definition>2304301 - Disclosure - Collaboration 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="CollaborationAgreementsTevaNarrativeDetails" roleURI="http://www.regeneron.com/role/CollaborationAgreementsTevaNarrativeDetails">
        <link:definition>2404415 - Disclosure - Collaboration 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="CondensedConsolidatedBalanceSheetsUnaudited" roleURI="http://www.regeneron.com/role/CondensedConsolidatedBalanceSheetsUnaudited">
        <link:definition>1001000 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited)</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="CondensedConsolidatedBalanceSheetsUnauditedParenthetical" roleURI="http://www.regeneron.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical">
        <link:definition>1001501 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (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="CondensedConsolidatedStatementsOfCashFlowsUnaudited" roleURI="http://www.regeneron.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited">
        <link:definition>1004000 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited)</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="CondensedConsolidatedStatementsOfOperationsAndComprehensiveIncomeUnaudited" roleURI="http://www.regeneron.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveIncomeUnaudited">
        <link:definition>1002000 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited)</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="ConsolidatedStatementsOfStockholdersEquityUnaudited" roleURI="http://www.regeneron.com/role/ConsolidatedStatementsOfStockholdersEquityUnaudited">
        <link:definition>1003000 - Statement - CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited)</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="Cover" roleURI="http://www.regeneron.com/role/Cover">
        <link:definition>0001000 - 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="FairValueMeasurements" roleURI="http://www.regeneron.com/role/FairValueMeasurements">
        <link:definition>2109100 - 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="FairValueMeasurementsNarrativeDetails" roleURI="http://www.regeneron.com/role/FairValueMeasurementsNarrativeDetails">
        <link:definition>2409403 - 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="FairValueMeasurementsScheduleOfAssetsMeasuredAtFairValueOnRecurringBasisDetails" roleURI="http://www.regeneron.com/role/FairValueMeasurementsScheduleOfAssetsMeasuredAtFairValueOnRecurringBasisDetails">
        <link:definition>2409402 - 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="FairValueMeasurementsTables" roleURI="http://www.regeneron.com/role/FairValueMeasurementsTables">
        <link:definition>2309301 - 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="IncomeTaxes" roleURI="http://www.regeneron.com/role/IncomeTaxes">
        <link:definition>2120100 - 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="IncomeTaxesDetails" roleURI="http://www.regeneron.com/role/IncomeTaxesDetails">
        <link:definition>2420402 - Disclosure - Income Taxes (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="InterimFinancialStatements" roleURI="http://www.regeneron.com/role/InterimFinancialStatements">
        <link:definition>2101100 - Disclosure - Interim Financial Statements</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="InterimFinancialStatementsPolicies" roleURI="http://www.regeneron.com/role/InterimFinancialStatementsPolicies">
        <link:definition>2201201 - Disclosure - Interim Financial Statements (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="InterimFinancialStatementsScheduleOfBalanceSheetDataDetails" roleURI="http://www.regeneron.com/role/InterimFinancialStatementsScheduleOfBalanceSheetDataDetails">
        <link:definition>2401404 - Disclosure - Interim Financial Statements - Schedule of Balance Sheet Data (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="InterimFinancialStatementsScheduleOfCashFlowsDataDetails" roleURI="http://www.regeneron.com/role/InterimFinancialStatementsScheduleOfCashFlowsDataDetails">
        <link:definition>2401406 - Disclosure - Interim Financial Statements - Schedule of Cash Flows Data (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="InterimFinancialStatementsScheduleOfStatementsOfOperationsDataDetails" roleURI="http://www.regeneron.com/role/InterimFinancialStatementsScheduleOfStatementsOfOperationsDataDetails">
        <link:definition>2401405 - Disclosure - Interim Financial Statements - Schedule of Statements of Operations Data (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="InterimFinancialStatementsTables" roleURI="http://www.regeneron.com/role/InterimFinancialStatementsTables">
        <link:definition>2301302 - Disclosure - Interim Financial Statements (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="Inventories" roleURI="http://www.regeneron.com/role/Inventories">
        <link:definition>2112100 - 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="InventoriesScheduleOfInventoriesDetails" roleURI="http://www.regeneron.com/role/InventoriesScheduleOfInventoriesDetails">
        <link:definition>2412402 - 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="InventoriesTables" roleURI="http://www.regeneron.com/role/InventoriesTables">
        <link:definition>2312301 - 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="LegalMatters" roleURI="http://www.regeneron.com/role/LegalMatters">
        <link:definition>2126100 - 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="LegalMattersDetails" roleURI="http://www.regeneron.com/role/LegalMattersDetails">
        <link:definition>2426401 - 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="MarketableSecurities" roleURI="http://www.regeneron.com/role/MarketableSecurities">
        <link:definition>2108100 - 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="MarketableSecuritiesNarrativeDetails" roleURI="http://www.regeneron.com/role/MarketableSecuritiesNarrativeDetails">
        <link:definition>2408405 - 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="MarketableSecuritiesScheduleOfDebtSecuritiesBasedOnContractualMaturityDatesDetails" roleURI="http://www.regeneron.com/role/MarketableSecuritiesScheduleOfDebtSecuritiesBasedOnContractualMaturityDatesDetails">
        <link:definition>2408403 - 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>2408404 - 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="MarketableSecuritiesScheduleOfInvestmentsInAvailableForSaleDebtSecuritiesDetails" roleURI="http://www.regeneron.com/role/MarketableSecuritiesScheduleOfInvestmentsInAvailableForSaleDebtSecuritiesDetails">
        <link:definition>2408402 - 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="MarketableSecuritiesTables" roleURI="http://www.regeneron.com/role/MarketableSecuritiesTables">
        <link:definition>2308301 - 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="NetIncomePerShare" roleURI="http://www.regeneron.com/role/NetIncomePerShare">
        <link:definition>2107100 - 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="NetIncomePerShareScheduleOfAntidilutiveSecuritiesExcludedFromComputationDetails" roleURI="http://www.regeneron.com/role/NetIncomePerShareScheduleOfAntidilutiveSecuritiesExcludedFromComputationDetails">
        <link:definition>2407403 - 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="NetIncomePerShareScheduleOfBasicAndDilutedNetIncomePerShareDetails" roleURI="http://www.regeneron.com/role/NetIncomePerShareScheduleOfBasicAndDilutedNetIncomePerShareDetails">
        <link:definition>2407402 - 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="NetIncomePerShareTables" roleURI="http://www.regeneron.com/role/NetIncomePerShareTables">
        <link:definition>2307301 - 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="ProductSales" roleURI="http://www.regeneron.com/role/ProductSales">
        <link:definition>2103100 - 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="ProductSalesScheduleOfConcentrationOfRiskByRiskFactorDetails" roleURI="http://www.regeneron.com/role/ProductSalesScheduleOfConcentrationOfRiskByRiskFactorDetails">
        <link:definition>2403403 - 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="ProductSalesScheduleOfNetProductSalesDetails" roleURI="http://www.regeneron.com/role/ProductSalesScheduleOfNetProductSalesDetails">
        <link:definition>2403402 - 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="ProductSalesTables" roleURI="http://www.regeneron.com/role/ProductSalesTables">
        <link:definition>2303301 - 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="StatementOfCashFlows" roleURI="http://www.regeneron.com/role/StatementOfCashFlows">
        <link:definition>2124100 - 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="StatementOfCashFlowsNarrativeDetails" roleURI="http://www.regeneron.com/role/StatementOfCashFlowsNarrativeDetails">
        <link:definition>2424403 - Disclosure - Statement of Cash Flows - 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="StatementOfCashFlowsScheduleOfReconciliationOfCashCashEquivalentsAndRestrictedCashDetails" roleURI="http://www.regeneron.com/role/StatementOfCashFlowsScheduleOfReconciliationOfCashCashEquivalentsAndRestrictedCashDetails">
        <link:definition>2424402 - 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="StatementOfCashFlowsTables" roleURI="http://www.regeneron.com/role/StatementOfCashFlowsTables">
        <link:definition>2324301 - 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="StockholdersEquity" roleURI="http://www.regeneron.com/role/StockholdersEquity">
        <link:definition>2121100 - 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="StockholdersEquityDetails" roleURI="http://www.regeneron.com/role/StockholdersEquityDetails">
        <link:definition>2421401 - Disclosure - Stockholders' Equity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element abstract="true" id="regn_A165PatentMember" name="A165PatentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_A487PatentMember" name="A487PatentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_A741PatentMember" name="A741PatentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_AccruedCapitalExpenditures" name="AccruedCapitalExpenditures" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_Amgenv.s.RegeneronMember" name="Amgenv.s.RegeneronMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_AmountsRecognizedInConnectionWithUpFrontPaymentsMember" name="AmountsRecognizedInConnectionWithUpFrontPaymentsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ArcalystNetProductSalesMember" name="ArcalystNetProductSalesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_BayerCollaborationAgreementMember" name="BayerCollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_BesseMedicalMember" name="BesseMedicalMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ClassificationOfInvestmentAxis" name="ClassificationOfInvestmentAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ClassificationOfInvestmentDomain" name="ClassificationOfInvestmentDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_CollaborationandContractManufacturingMember" name="CollaborationandContractManufacturingMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ContractWithCustomerandCollaboratorAssetAndLiabilityTableTextBlock" name="ContractWithCustomerandCollaboratorAssetAndLiabilityTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_DupilumabREGN3500EligibleInvestmentsMember" name="DupilumabREGN3500EligibleInvestmentsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_EyleaNetProductSalesMember" name="EyleaNetProductSalesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_GainContingencyClaimsInvalidatedNumber" name="GainContingencyClaimsInvalidatedNumber" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_GainContingencyInterPartesReviewFiledNumber" name="GainContingencyInterPartesReviewFiledNumber" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_GrossSalesRevenueMember" name="GrossSalesRevenueMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LIBTAYONetProductSalesMember" name="LIBTAYONetProductSalesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LibtayoDevelopmentMember" name="LibtayoDevelopmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_LossContingencyClaimsInvalidNumber" name="LossContingencyClaimsInvalidNumber" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_LossContingencyDamagesSoughtperunitproduced." name="LossContingencyDamagesSoughtperunitproduced." nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_LossContingencyPercentageOfDamagesResponsibleFor" name="LossContingencyPercentageOfDamagesResponsibleFor" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_MaximumAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels" name="MaximumAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_Maximumsharesthecollaboratorcouldsell" name="Maximumsharesthecollaboratorcouldsell" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_McKessonCorporationMember" name="McKessonCorporationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_NetProfitInConnectionWithCommercializationMember" name="NetProfitInConnectionWithCommercializationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherCollaborationAgreementsMember" name="OtherCollaborationAgreementsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherMember" name="OtherMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherRevenueMember" name="OtherRevenueMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfRoyaltyPaymentThatCanBeOffset" name="PercentageOfRoyaltyPaymentThatCanBeOffset" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfTrialCostsBorneByCollaboratingParty" name="PercentageOfTrialCostsBorneByCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfTrialCostsBorneByEntity" name="PercentageOfTrialCostsBorneByEntity" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" name="PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PraluentCrossLicenseAndCommercializationAgreementMember" name="PraluentCrossLicenseAndCommercializationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ProductSalesandConcentrationRiskTextBlock" name="ProductSalesandConcentrationRiskTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RegeneronsShareOfResearchAndDevelopmentExpensesMember" name="RegeneronsShareOfResearchAndDevelopmentExpensesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ReimbursementForManufacturingOfCommercialSuppliesMember" name="ReimbursementForManufacturingOfCommercialSuppliesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ReimbursementOfCommercializationRelatedExpensesMember" name="ReimbursementOfCommercializationRelatedExpensesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ReimbursementOfOtherExpenses" name="ReimbursementOfOtherExpenses" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_ReimbursementOfResearchAndDevelopmentExpense" name="ReimbursementOfResearchAndDevelopmentExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ReimbursementOfResearchAndDevelopmentExpensesMember" name="ReimbursementOfResearchAndDevelopmentExpensesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ReimbursementOfSellingGeneralAndAdministrativeExpense" name="ReimbursementOfSellingGeneralAndAdministrativeExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RestrictedMember" name="RestrictedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RevenuebasedonpercentageofannualsalesinJapan" name="RevenuebasedonpercentageofannualsalesinJapan" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RoyaltyPercentageToBeReceivedOnNetProductSalesOutsideOfUnitedStates" name="RoyaltyPercentageToBeReceivedOnNetProductSalesOutsideOfUnitedStates" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofiCollaborationAgreementAntibodyMember" name="SanofiCollaborationAgreementAntibodyMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofiCollaborationAgreementImmunooncologyMember" name="SanofiCollaborationAgreementImmunooncologyMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofiCollaborationAgreementMember" name="SanofiCollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofiMember" name="SanofiMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofisShareofLibtayoU.S.GrossProfitsMember" name="SanofisShareofLibtayoU.S.GrossProfitsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ShareOfProfitLossesInConnectionWithCommercializationMember" name="ShareOfProfitLossesInConnectionWithCommercializationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ShareRepurchaseProgramMember" name="ShareRepurchaseProgramMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StockIssuedDistributedDuringPeriodSharesEmployeeBenefitPlan" name="StockIssuedDistributedDuringPeriodSharesEmployeeBenefitPlan" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StockIssuedDistributedDuringPeriodValueEmployeeBenefitPlan" name="StockIssuedDistributedDuringPeriodValueEmployeeBenefitPlan" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_TevaPharmaceuticalsCollaborationAgreementMember" name="TevaPharmaceuticalsCollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_UnrestrictedMember" name="UnrestrictedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_UnsatisfiedObligation" name="UnsatisfiedObligation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
</xsd:schema>
