<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-05-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001756262</issuerCik>
        <issuerName>TransMedics Group, Inc.</issuerName>
        <issuerTradingSymbol>TMDX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001508051</rptOwnerCik>
            <rptOwnerName>Flagship Ventures Fund IV General Partner LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FLAGSHIP PIONEERING, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>55 CAMBRIDGE PARKWAY, SUITE 800E</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02142</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001503559</rptOwnerCik>
            <rptOwnerName>Flagship Ventures Fund IV, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FLAGSHIP PIONEERING INC.</rptOwnerStreet1>
            <rptOwnerStreet2>55 CAMBRIDGE PARKWAY, SUITE 800E</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02142</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001508053</rptOwnerCik>
            <rptOwnerName>Flagship Ventures 2007 General Partner LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FLAGSHIP PIONEERING INC.</rptOwnerStreet1>
            <rptOwnerStreet2>55 CAMBRIDGE PARKWAY, SUITE 800E</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02142</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001508052</rptOwnerCik>
            <rptOwnerName>Flagship Ventures Fund 2007, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FLAGSHIP PIONEERING INC.</rptOwnerStreet1>
            <rptOwnerStreet2>55 CAMBRIDGE PARKWAY, SUITE 800E</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02142</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001222012</rptOwnerCik>
            <rptOwnerName>AFEYAN NOUBAR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FLAGSHIP PIONEERING, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>55 CAMBRIDGE PARKWAY, SUITE 800E</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02142</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-05-06</value>
            </transactionDate>
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            <transactionCoding>
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            <transactionTimeliness>
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                </transactionShares>
                <transactionPricePerShare>
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            </transactionAmounts>
            <postTransactionAmounts>
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            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Flagship Ventures Fund IV, L.P.</value>
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                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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            <postTransactionAmounts>
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                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
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                </directOrIndirectOwnership>
                <natureOfOwnership>
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                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
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            <deemedExecutionDate></deemedExecutionDate>
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            <ownershipNature>
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                <natureOfOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
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                <transactionShares>
                    <value>1682665</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>132817</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Flagship Ventures Fund 2007, L.P.</value>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Common Stock reported herein being disposed of is common stock of TransMedics, Inc. Immediately prior to the closing of the Issuer's initial public offering, pursuant to the Agreement and Plan of Merger and Reorganization by and among the Issuer, TransMedics, Inc. and TMDX, Inc., dated April 15, 2019 (the &quot;Merger Agreement&quot;) such common stock of TransMedics, Inc. was converted into shares of common stock of the Issuer on a 3.5-for-one basis.</footnote>
        <footnote id="F2">The Preferred Stock reported herein is preferred stock of TransMedics, Inc. Immediately prior to the closing of the Issuer's initial public offering, pursuant to the Merger Agreement, such Series C, D and F preferred stock of TransMedics, Inc. was converted into shares of common stock of the Issuer based on (i) the one-for-one ratio on which such shares of preferred stock of TransMedics Inc. were convertible into shares of common stock of TransMedics Inc. according to their terms and (ii) the 3.5-for-one ratio on which shares of common stock of TransMedics, Inc. were converted into shares of common stock of the Issuer. The Preferred Stock has no expiration date.</footnote>
        <footnote id="F3">The Preferred Stock reported herein is preferred stock of TransMedics, Inc. Immediately prior to the closing of the Issuer's initial public offering, pursuant to the Merger Agreement, each outstanding share of Series B-1 preferred stock of TransMedics, Inc. was converted into shares of common stock of the Issuer based on (i) the ratio on which such shares of preferred stock of TransMedics Inc. were convertible into shares of common stock of TransMedics Inc. according to their terms, determined by dividing the original issue price of $3.416 per share by a conversion price of $12.365, and (ii) the 3.5-for-one ratio on which shares of common stock of TransMedics, Inc. were converted into shares of common stock of the Issuer. The Preferred Stock has no expiration date.</footnote>
        <footnote id="F4">Shares held by Flagship Ventures Fund IV, L.P. (&quot;Flagship Fund IV&quot;). Flagship Ventures Fund IV General Partner LLC (&quot;Flagship Fund IV GP&quot;) is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. is a manager of Flagship Fund IV GP and, for purposes of Flagship Fund IV's investment in the Issuer, Dr. Afeyan may be deemed to have voting and investment power with respect to all shares held by Flagship Fund IV. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent, if any, of his or its pecuniary interest therein.</footnote>
        <footnote id="F5">Shares held by Flagship Ventures Fund 2007, L.P. (&quot;Flagship Fund 2007&quot;). Flagship Ventures 2007 General Partner LLC (&quot;Flagship Fund 2007 GP&quot;) is the general partner of Flagship Fund 2007. Dr. Afeyan is a manager of Flagship Fund 2007 GP and, for purposes of Flagship Fund 2007's investment in the Issuer, Dr. Afeyan may be deemed to have voting and investment power with respect to all shares held by Flagship Fund 2007. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent, if any, of his or its pecuniary interest therein.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Flagship Ventures Fund IV General Partner LLC, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager</signatureName>
        <signatureDate>2019-05-06</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Flagship Ventures Fund IV, L.P., By Flagship Ventures Fund IV General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager</signatureName>
        <signatureDate>2019-05-06</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Flagship Ventures Fund 2007 General Partner LLC, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager</signatureName>
        <signatureDate>2019-05-06</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Flagship Ventures Fund 2007, L.P., By Flagship Ventures Fund 2007 General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager</signatureName>
        <signatureDate>2019-05-06</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Noubar B. Afeyan</signatureName>
        <signatureDate>2019-05-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
