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      <filerInfo>
        <filer>
          <filerCredentials>
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            <ccc>XXXXXXXX</ccc>
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        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
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        <issuerName>THERMO FISHER SCIENTIFIC INC.</issuerName>
        <secFileNumber>001-08002</secFileNumber>
        <issuerAddress>
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          <com:city>WALTHAM</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>02451</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>7816221000</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>CASPER MARC N</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Officer</relationshipToIssuer>
          <relationshipToIssuer>Director</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Fidelity Brokerage Services LLC</name>
          <address>
            <com:street1>900 Salem Street</com:street1>
            <com:city>Smithfield</com:city>
            <com:stateOrCountry>RI</com:stateOrCountry>
            <com:zipCode>02917</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
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        <aggregateMarketValue>3263674.42</aggregateMarketValue>
        <noOfUnitsOutstanding>382500265</noOfUnitsOutstanding>
        <approxSaleDate>11/01/2024</approxSaleDate>
        <securitiesExchangeName>NYSE</securitiesExchangeName>
      </securitiesInformation>
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        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>11/01/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Option Granted - 02/27/2018</natureOfAcquisitionTransaction>
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        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>5850</amountOfSecuritiesAcquired>
        <paymentDate>11/01/2024</paymentDate>
        <natureOfPayment>Cash</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Marc N. Casper</name>
          <address>
            <com:street1>168 Third Avenue</com:street1>
            <com:city>Waltham</com:city>
            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02451</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>09/03/2024</saleDate>
        <amountOfSecuritiesSold>10000</amountOfSecuritiesSold>
        <grossProceeds>6087451.00</grossProceeds>
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            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02451</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>09/04/2024</saleDate>
        <amountOfSecuritiesSold>10000</amountOfSecuritiesSold>
        <grossProceeds>6081490.00</grossProceeds>
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      <securitiesSoldInPast3Months>
        <sellerDetails>
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            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02451</com:zipCode>
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        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>10/28/2024</saleDate>
        <amountOfSecuritiesSold>10000</amountOfSecuritiesSold>
        <grossProceeds>5542897.00</grossProceeds>
      </securitiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Marc N. Casper</name>
          <address>
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            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02451</com:zipCode>
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        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>10/29/2024</saleDate>
        <amountOfSecuritiesSold>10000</amountOfSecuritiesSold>
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      </securitiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Marc N. Casper</name>
          <address>
            <com:street1>168 Third Avenue</com:street1>
            <com:city>Waltham</com:city>
            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02451</com:zipCode>
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          <name>Marc N. Casper</name>
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      </securitiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>11/01/2024</noticeDate>
        <planAdoptionDates>
          <planAdoptionDate>08/07/2024</planAdoptionDate>
        </planAdoptionDates>
        <signature>/s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Marc N. Casper</signature>
      </noticeSignature>
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metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 6499}]
text: 144
  0001216055
  XXXXXXXX
  LIVE
  0000097745
  THERMO FISHER SCIENTIFIC INC.
  001-08002
  168 THIRD AVENUE
  WALTHAM
  MA
  02451
  7816221000
  CASPER MARC N
  Officer
  Director
  Common
  Fidelity Brokerage Services LLC
  900 Salem Street
  Smithfield
  RI
  02917
  5850
  3263674.42
  382500265
  11/01/2024
  NYSE
  Common
  11/01/2024
  Option Granted - 02/27/2018
  Issuer
  N
  5850
  11/01/2024
  Cash
  N
  Marc N. Casper
  168 Third Avenue
  Waltham
  MA
  02451
  Common
  09/03/2024
  10000
  6087451.00
  Marc N. Casper
  168 Third Avenue
  Waltham
  MA
  02451
  Common
  09/04/2024
  10000
  6081490.00
  Marc N. Casper
  168 Third Avenue
  Waltham
  MA
  02451
  Common
  10/28/2024
  10000
  5542897.00
  Marc N. Casper
  168 Third Avenue
  Waltham
  MA
  02451
  Common
  10/29/2024
  10000
  5506211.00
  Marc N. Casper
  168 Third Avenue
  Waltham
  MA
  02451
  Common
  10/30/2024
  10000
  5518285.00
  Marc N. Casper
  168 Third Avenue
  Waltham
  MA
  02451
  Common
  10/31/2024
  10000
  5492025.00
  11/01/2024
  08/07/2024
  /s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Marc N. Casper