content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <!-- Generated by Workiva -->
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001187443</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0000872589</issuerCik>
        <issuerName>Regeneron Pharmaceuticals Inc</issuerName>
        <secFileNumber>000-19034</secFileNumber>
        <issuerAddress>
          <com:street1>777 Old Saw Mill River Road</com:street1>
          <com:street2>Tarrytown</com:street2>
          <com:city>New York</com:city>
          <com:stateOrCountry>NY</com:stateOrCountry>
          <com:zipCode>10591</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>914-847-7000</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Arthur Ryan</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Affiliate</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>J.P. Morgan Securities LLC</name>
          <address>
            <com:street1>390 Madison Avenue</com:street1>
            <com:street2>6th Floor</com:street2>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10017</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>300</noOfUnitsSold>
        <aggregateMarketValue>249237</aggregateMarketValue>
        <noOfUnitsOutstanding>107128838</noOfUnitsOutstanding>
        <approxSaleDate>11/07/2023</approxSaleDate>
        <securitiesExchangeName>Nasdaq</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>08/22/2013</acquiredDate>
        <natureOfAcquisitionTransaction>Stock award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>300</amountOfSecuritiesAcquired>
        <paymentDate>08/22/2013</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>11/07/2023</noticeDate>
        <planAdoptionDates>
          <planAdoptionDate>08/07/2023</planAdoptionDate>
        </planAdoptionDates>
        <signature>/s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for Arthur Ryan</signature>
      </noticeSignature>
    </formData>
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text: 144
  0001187443
  XXXXXXXX
  LIVE
  0000872589
  Regeneron Pharmaceuticals Inc
  000-19034
  777 Old Saw Mill River Road
  Tarrytown
  New York
  NY
  10591
  914-847-7000
  Arthur Ryan
  Affiliate
  Common
  J.P. Morgan Securities LLC
  390 Madison Avenue
  6th Floor
  New York
  NY
  10017
  300
  249237
  107128838
  11/07/2023
  Nasdaq
  Common
  08/22/2013
  Stock award
  Issuer
  N
  300
  08/22/2013
  Compensation
  Y
  11/07/2023
  08/07/2023
  /s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for Arthur Ryan