<SEC-DOCUMENT>0000899243-23-007198.txt : 20230306
<SEC-HEADER>0000899243-23-007198.hdr.sgml : 20230306
<ACCEPTANCE-DATETIME>20230306173152
ACCESSION NUMBER:		0000899243-23-007198
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20230302
FILED AS OF DATE:		20230306
DATE AS OF CHANGE:		20230306

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KURIYEL RALF
		CENTRAL INDEX KEY:			0001733143

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14656
		FILM NUMBER:		23710121

	MAIL ADDRESS:	
		STREET 1:		41 SEYON ST
		STREET 2:		BLDG 1, STE. 100
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02452

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			REPLIGEN CORP
		CENTRAL INDEX KEY:			0000730272
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				042729386
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		41 SEYON STREET
		STREET 2:		BUILDING 1, SUITE 100
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02453
		BUSINESS PHONE:		7814499560

	MAIL ADDRESS:	
		STREET 1:		41 SEYON STREET
		STREET 2:		BUILDING 1, SUITE 100
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02453
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
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    <periodOfReport>2023-03-02</periodOfReport>

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    <issuer>
        <issuerCik>0000730272</issuerCik>
        <issuerName>REPLIGEN CORP</issuerName>
        <issuerTradingSymbol>RGEN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001733143</rptOwnerCik>
            <rptOwnerName>KURIYEL RALF</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O REPLIGEN CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>41 SEYON ST., BLDG 1, STE 100</rptOwnerStreet2>
            <rptOwnerCity>WALTHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02453</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior VP, R&amp;D</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <transactionDate>
                <value>2023-03-02</value>
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                <transactionShares>
                    <value>3468</value>
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                <transactionPricePerShare>
                    <value>0.00</value>
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        <nonDerivativeTransaction>
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                    <value>188.00</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
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    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>180.48</value>
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                <value>2023-03-02</value>
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                <value></value>
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            <transactionAmounts>
                <transactionShares>
                    <value>3591</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
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            <exerciseDate>
                <footnoteId id="F4"/>
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            <expirationDate>
                <value>2033-03-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3591</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>3591</value>
                </sharesOwnedFollowingTransaction>
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    </derivativeTable>

    <footnotes>
        <footnote id="F1">Mr. Kuriyel was awarded 3,468 restricted stock units. Each restricted stock unit represents a contingent right to receive one share of Repligen Corporation's Common Stock. The restricted stock units vest in equal annual instalments over a three-year period beginning on the first anniversary of the grant date. The restricted stock units may be settled only by delivering shares of Repligen Corporation's Common Stock, and thus, the grant is being reported in Table 1 as allowed per SEC guidance.</footnote>
        <footnote id="F2">Represents 375 shares issued pursuant to a Performance Stock Unit (&quot;PSU&quot;) award granted to the Issuer on January 1, 2022, and 3,216 shares issued pursuant to a PSU award granted to the Issuer on February 27, 2020. The Compensation Committee authorized the issuance of the underlying shares based upon the Issuer's achievement of pre-established performance criteria set forth in the PSU awards.</footnote>
        <footnote id="F3">Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the settlement of the PSUs.</footnote>
        <footnote id="F4">One third of the stock options will vest and become exercisable annually on March 2, 2024, March 2, 2025, and March 2, 2026.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Kimberly Brown (Attorney in Fact)</signatureName>
        <signatureDate>2023-03-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
