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  <xsd:element abstract="true" id="regn_GrosssalesrevenueMember" name="GrosssalesrevenueMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ImputedInterestRateApplicableToFacilityLeaseObligation" name="ImputedInterestRateApplicableToFacilityLeaseObligation" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_IncomeTaxExpenseBenefitResultingFromProvisionInAmericanRecoveryAndReinvestmentActOf2009" name="IncomeTaxExpenseBenefitResultingFromProvisionInAmericanRecoveryAndReinvestmentActOf2009" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_IncrementalCommonSharesAttributableToNonvestedRestrictedShares" name="IncrementalCommonSharesAttributableToNonvestedRestrictedShares" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Initialtermoflease" name="Initialtermoflease" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_InterestExpenseAssociatedWithConvertibleNotesTableTextBlock" name="InterestExpenseAssociatedWithConvertibleNotesTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_InterestExpenseInConnectionWithFacilityLeaseObligation" name="InterestExpenseInConnectionWithFacilityLeaseObligation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_InternationalGovernmentObligationsFairValueDisclosure" name="InternationalGovernmentObligationsFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_InternationalgovernmentagencyobligationsMember" name="InternationalgovernmentagencyobligationsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_IssuanceCosts" name="IssuanceCosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_LeaseRenewalEscalationPercentage" name="LeaseRenewalEscalationPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_Leaseextensionterms" name="Leaseextensionterms" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LicenseAgreementWithAstellasPharmaIncMember" name="LicenseAgreementWithAstellasPharmaIncMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LicenseAgreementWithAstrazenecaUkLimitedMember" name="LicenseAgreementWithAstrazenecaUkLimitedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LicenseAgreementWithGenentechMember" name="LicenseAgreementWithGenentechMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LicenseagreementwithGenentechEYLEAMember" name="LicenseagreementwithGenentechEYLEAMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LongTermIncentivePlan2000Member" name="LongTermIncentivePlan2000Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LossContingenciesByGeographicAreaAxis" name="LossContingenciesByGeographicAreaAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LossContingenciesByGeographicAreaDomain" name="LossContingenciesByGeographicAreaDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_MarketableDebtSecuritiesCollateral" name="MarketableDebtSecuritiesCollateral" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_MarketingApprovalMember" name="MarketingApprovalMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_MaximumAmountOfMilestonePaymentsThatMayBeReceivedIfCertainSalesAreAchieved" name="MaximumAmountOfMilestonePaymentsThatMayBeReceivedIfCertainSalesAreAchieved" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" 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_MaximumAmountOfSubstantiveMilestonePaymentsThatMayBeReceivedRelatingToMarketingApprovals" name="MaximumAmountOfSubstantiveMilestonePaymentsThatMayBeReceivedRelatingToMarketingApprovals" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_MaximumPercentageOfOutstandingSharesThatMayBeAcquiredUnderStandstillProvisions" name="MaximumPercentageOfOutstandingSharesThatMayBeAcquiredUnderStandstillProvisions" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_Maximumlevelsofannualsalesforwhichsalesmilestonepaymentsmaybereceived" name="Maximumlevelsofannualsalesforwhichsalesmilestonepaymentsmaybereceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_MinimumPaymentsExpectedToBeReceivedUnderAgreement" name="MinimumPaymentsExpectedToBeReceivedUnderAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_Minimumadvancenoticerequiredtoterminatecollaborationagreement" name="Minimumadvancenoticerequiredtoterminatecollaborationagreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_MunicipalBondsFairValueDisclosure" name="MunicipalBondsFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_NameOfLeaseAxis" name="NameOfLeaseAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_NameOfLeaseDomain" name="NameOfLeaseDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_NetCarryingAmountOfLiabilityComponentAbstract" name="NetCarryingAmountOfLiabilityComponentAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NetProfitLossFromCommercializationOfProductsUnderCollaborationAgreement" name="NetProfitLossFromCommercializationOfProductsUnderCollaborationAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_NewLaboratoryAndOfficeFacilitiesMember" name="NewLaboratoryAndOfficeFacilitiesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NonCashInterestExpense" name="NonCashInterestExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_NonExclusiveLicenseAgreementTerm" name="NonExclusiveLicenseAgreementTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_NonPerformanceBasedStockOptionsMember" name="NonPerformanceBasedStockOptionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NonRefundableAdvancePaymentMadeUnderLicenseAgreement" name="NonRefundableAdvancePaymentMadeUnderLicenseAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberOfDaysOfAdvanceWrittenNoticeToTerminateAgreement" name="NumberOfDaysOfAdvanceWrittenNoticeToTerminateAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberOfMarketableSecuritiesHeld" name="NumberOfMarketableSecuritiesHeld" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_NumberOfNewBuildingsLeased" name="NumberOfNewBuildingsLeased" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberOfRenewalOptions" name="NumberOfRenewalOptions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_NumberOfSharesOfCommonStockPurchasedInShares" name="NumberOfSharesOfCommonStockPurchasedInShares" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_NumberOfTherapeuticAntibodiesCurrentlyUnderDevelopment" name="NumberOfTherapeuticAntibodiesCurrentlyUnderDevelopment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_Numberoffamiliesofnovelantibodies" name="Numberoffamiliesofnovelantibodies" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Numberofnewbuildingstobeconstructed" name="Numberofnewbuildingstobeconstructed" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Numberofsalesmilestones" name="Numberofsalesmilestones" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberofsharesofCommonStockpurchased" name="NumberofsharesofCommonStockpurchased" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Optinpayment" name="Optinpayment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_OtherCollaborationRevenue" name="OtherCollaborationRevenue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherDeferredRevenueAgreementsMember" name="OtherDeferredRevenueAgreementsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherSalesRelatedDeductionsMember" name="OtherSalesRelatedDeductionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PDGFMember" name="PDGFMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PDGFRbetaoutsidetheUSMember" name="PDGFRbetaoutsidetheUSMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfOutstandingSharesOrVotingRightsUnderAmendedInvestorAgreement" name="PercentageOfOutstandingSharesOrVotingRightsUnderAmendedInvestorAgreement" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfOutstandingSharesthattheCompanyisrequiredtoappointanindividualagreeduponbytheCompanyandtheCollaboratortotheCompanysboardofdirectors" name="PercentageOfOutstandingSharesthattheCompanyisrequiredtoappointanindividualagreeduponbytheCompanyandtheCollaboratortotheCompanysboardofdirectors" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfPromptPayDiscountCompanyAccrues" name="PercentageOfPromptPayDiscountCompanyAccrues" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfStartUpCostsOfTotalContractValueMaximum" name="PercentageOfStartUpCostsOfTotalContractValueMaximum" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfStartUpCostsOfTotalContractValueMinimum" name="PercentageOfStartUpCostsOfTotalContractValueMinimum" 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_PercentageOfTrialCostsToBeReimbursedDueToProfitabilityOfAgreement" name="PercentageOfTrialCostsToBeReimbursedDueToProfitabilityOfAgreement" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageofdevelopmentcostfortheterritoryoutsidetheUnitedStatestobepaidforunderthecollaboration" name="PercentageofdevelopmentcostfortheterritoryoutsidetheUnitedStatestobepaidforunderthecollaboration" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Percentageofdevelopmentexpensestobereimbursedduetoterminationofcollaborationagreement" name="Percentageofdevelopmentexpensestobereimbursedduetoterminationofcollaborationagreement" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Percentageofdevelopmentmilestonepaymentstobereimbursedduetocollaborationagreement" name="Percentageofdevelopmentmilestonepaymentstobereimbursedduetocollaborationagreement" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PerformanceBasedStockOptionsMember" name="PerformanceBasedStockOptionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" name="PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodOfNoticeToOptOutOfFurtherDevelopmentAndOrCommercialization" name="PeriodOfNoticeToOptOutOfFurtherDevelopmentAndOrCommercialization" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodOfNoticeToOptOutOfFurtherDevelopmentUponEnteringOfJointDevelopmentProduct" name="PeriodOfNoticeToOptOutOfFurtherDevelopmentUponEnteringOfJointDevelopmentProduct" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PhantomStockMember" name="PhantomStockMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PricingApprovalMember" name="PricingApprovalMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ProceedsFromConvertibleDebtNetOfIssuanceCosts" name="ProceedsFromConvertibleDebtNetOfIssuanceCosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_PurchaseOfConvertibleNoteHedges" name="PurchaseOfConvertibleNoteHedges" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RebatesAndChargebacksMember" name="RebatesAndChargebacksMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RecognitionPeriodForAdvancePayment" name="RecognitionPeriodForAdvancePayment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RentChargesForUtilitiesRealEstateTaxesAndOperatingExpense" name="RentChargesForUtilitiesRealEstateTaxesAndOperatingExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingAgreementsAxis" name="ResearchCollaborationAndLicensingAgreementsAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingAgreementsDomain" name="ResearchCollaborationAndLicensingAgreementsDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingArrangementsLineItems" name="ResearchCollaborationAndLicensingArrangementsLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingArrangementsTable" name="ResearchCollaborationAndLicensingArrangementsTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" 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_RevenueAndConcentrationRiskDisclosureTextBlock" name="RevenueAndConcentrationRiskDisclosureTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RevenueDisclosureTable" name="RevenueDisclosureTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" 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_RoyaltyRateMaximum" name="RoyaltyRateMaximum" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RoyaltyRateMinimum" name="RoyaltyRateMinimum" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Royaltypaymentpercentageofcumulativesale1sttier" name="Royaltypaymentpercentageofcumulativesale1sttier" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Royaltypaymentpercentageofsales2ndtier" name="Royaltypaymentpercentageofsales2ndtier" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement1sttierMember" name="Salesachievement1sttierMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement2ndtierMember" name="Salesachievement2ndtierMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement3rdtierMember" name="Salesachievement3rdtierMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Salesrangemaximum1sttier" name="Salesrangemaximum1sttier" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Salesrangeminimum1sttier" name="Salesrangeminimum1sttier" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" 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_ScheduleOfFacilityLeasesLineItems" name="ScheduleOfFacilityLeasesLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ScheduleOfFacilityLeasesTable" name="ScheduleOfFacilityLeasesTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" name="ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePricesAndWeightedAverageGrantDateFairValueTableTextBlock" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePricesAndWeightedAverageGrantDateFairValueTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedNumber" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedNumber" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodFromVestingDateAwardsMayBeReceived" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodFromVestingDateAwardsMayBeReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareOfLossesOutsideUnitedStatesForCollaboratingParty" name="ShareOfLossesOutsideUnitedStatesForCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareOfLossesOutsideUnitedStatesForCompany" name="ShareOfLossesOutsideUnitedStatesForCompany" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Sharepaidfortaxwithholdingforsharebasedcompensationrestrictedshares" name="Sharepaidfortaxwithholdingforsharebasedcompensationrestrictedshares" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StartingSpecifiedLevelsOfAnnualSalesAtWhichSalesMilestonePaymentsMayBeReceived" name="StartingSpecifiedLevelsOfAnnualSalesAtWhichSalesMilestonePaymentsMayBeReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived1sttier" name="Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived1sttier" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived2ndtier" name="Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived2ndtier" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived3rdtier" name="Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived3rdtier" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_SubstantiveMilestonePaymentToCompany" name="SubstantiveMilestonePaymentToCompany" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_SubstantiveMilestonePayments" name="SubstantiveMilestonePayments" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_TarrytownLeaseMember" name="TarrytownLeaseMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_TarrytownleaseAbstract" name="TarrytownleaseAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_TechnologyLicensingAgreementsAbstract" name="TechnologyLicensingAgreementsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_TechnologyLicensingAgreementsTextBlock" name="TechnologyLicensingAgreementsTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_USFederalAndNewYorkStateMember" name="USFederalAndNewYorkStateMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_USGovernmentGuaranteedCorporateBondsFairValueDisclosure" name="USGovernmentGuaranteedCorporateBondsFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_USGovernmentGuaranteedCorporateBondsMember" name="USGovernmentGuaranteedCorporateBondsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_USGovernmentObligationsFairValueDisclosure" name="USGovernmentObligationsFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_UnrestrictedMember" name="UnrestrictedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_VelocigeneAgreementMember" name="VelocigeneAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_WarrantTransactionsMember" name="WarrantTransactionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
</xsd:schema>
