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      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001884853</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
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      <issuerInfo>
        <issuerCik>0001049521</issuerCik>
        <issuerName>MERCURY SYSTEMS INC</issuerName>
        <secFileNumber>001-41194</secFileNumber>
        <issuerAddress>
          <com:street1>50 MINUTEMAN ROAD</com:street1>
          <com:city>ANDOVER</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>01810</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>9782561300</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Huber Thomas</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Former EVP and Chief Transformation Officer</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>
        <noOfUnitsSold>2519</noOfUnitsSold>
        <aggregateMarketValue>93133.73</aggregateMarketValue>
        <noOfUnitsOutstanding>58189929</noOfUnitsOutstanding>
        <approxSaleDate>09/25/2023</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>09/15/2023</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>2519</amountOfSecuritiesAcquired>
        <paymentDate>09/15/2023</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>09/25/2023</noticeDate>
        <signature>/s/Wade Moss, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Thomas Huber</signature>
      </noticeSignature>
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text: 144
  0001884853
  XXXXXXXX
  LIVE
  0001049521
  MERCURY SYSTEMS INC
  001-41194
  50 MINUTEMAN ROAD
  ANDOVER
  MA
  01810
  9782561300
  Huber Thomas
  Former EVP and Chief Transformation Officer
  Common
  Fidelity Brokerage Services LLC
  900 Salem Street
  Smithfield
  RI
  02917
  2519
  93133.73
  58189929
  09/25/2023
  NASDAQ
  Common
  09/15/2023
  Restricted Stock Vesting
  Issuer
  N
  2519
  09/15/2023
  Compensation
  Y
  09/25/2023
  /s/Wade Moss, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Thomas Huber