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    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001231657</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>ASLETT MARK</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Officer</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Fidelity Brokerage Services LLC</name>
        <address>
          <com:street1>100 Summer Street</com:street1>
          <com:city>Boston</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>02110</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>4765</noOfUnitsSold>
      <aggregateMarketValue>252440.65</aggregateMarketValue>
      <noOfUnitsOutstanding>58107888</noOfUnitsOutstanding>
      <approxSaleDate>02/21/2023</approxSaleDate>
      <securitiesExchangeName>NASDAQ</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>02/17/2023</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>4765</amountOfSecuritiesAcquired>
      <paymentDate>02/17/2023</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Mark Aslett</name>
        <address>
          <com:street1>50 Minuteman Road</com:street1>
          <com:city>Andover</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>01810</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <saleDate>02/16/2023</saleDate>
      <amountOfSecuritiesSold>4708</amountOfSecuritiesSold>
      <grossProceeds>255958.42</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Mark Aslett</name>
        <address>
          <com:street1>50 Minuteman Road</com:street1>
          <com:city>Andover</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>01810</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <saleDate>02/17/2023</saleDate>
      <amountOfSecuritiesSold>4685</amountOfSecuritiesSold>
      <grossProceeds>252472.31</grossProceeds>
    </securitiesSoldInPast3Months>
    <noticeSignature>
      <noticeDate>02/21/2023</noticeDate>
      <signature>/s/ Wade Moss, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Mark Aslett</signature>
    </noticeSignature>
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144
0001231657
XXXXXXXX
LIVE
0001049521
MERCURY SYSTEMS INC
001-41194
50 MINUTEMAN ROAD
ANDOVER
MA
01810
9782561300
ASLETT MARK
Officer
Common
Fidelity Brokerage Services LLC
100 Summer Street
Boston
MA
02110
4765
252440.65
58107888
02/21/2023
NASDAQ
Common
02/17/2023
Restricted Stock Vesting
Issuer
N
4765
02/17/2023
Compensation
N
Mark Aslett
50 Minuteman Road
Andover
MA
01810
Common
02/16/2023
4708
255958.42
Mark Aslett
50 Minuteman Road
Andover
MA
01810
Common
02/17/2023
4685
252472.31
02/21/2023
/s/ Wade Moss, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Mark Aslett