<SEC-DOCUMENT>0000899243-21-015429.txt : 20210408
<SEC-HEADER>0000899243-21-015429.hdr.sgml : 20210408
<ACCEPTANCE-DATETIME>20210408195543
ACCESSION NUMBER:		0000899243-21-015429
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20210406
FILED AS OF DATE:		20210408
DATE AS OF CHANGE:		20210408

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Bylund James
		CENTRAL INDEX KEY:			0001849642

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14656
		FILM NUMBER:		21816111

	MAIL ADDRESS:	
		STREET 1:		C/O REPLIGEN CORPORATION
		STREET 2:		41 SYON ST. BLDG. SUITE 100
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02453

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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-04-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001849642</rptOwnerCik>
            <rptOwnerName>Bylund James</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>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP, Global Operations &amp; IT</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-04-06</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>360</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>204.25</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6324</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Sale of shares in the open market to cover tax liability resulting from the release of restricted stock units.</footnote>
        <footnote id="F2">$204.25 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $204.07 to $204.30, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.</footnote>
    </footnotes>

    <remarks>Exhibit 24.1: Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Kimberly Brown (Attorney in Fact)</signatureName>
        <signatureDate>2021-04-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24.1
<SEQUENCE>2
<FILENAME>attachment1.htm
<DESCRIPTION>EX-24.1 DOCUMENT
<TEXT>
<HTML>
<HEAD>
</HEAD>
<BODY>
<PRE>
                               POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and
appoints each of Jon Snodgres, Kimberly Brown and Kenneth O'Brien the true and
lawful attorney-in-fact and agent, with full power of substitution and
resubstitution, for the undersigned and in the undersigned's name, place and
stead, in any and all capacities (until revoked in writing) to execute for and
on behalf of the undersigned, in any and all of the undersigned's capacities,
any and all statements on Forms 3, 4 and 5 with respect to the undersigned's
holdings of and transactions in securities issued by Repligen Corporation (the
"Company") in accordance with Sections 16(a) of the Securities Exchange Act of
1934, as amended (the "Exchange Act"), and any and all regulations promulgated
thereunder, and to file the same, with all exhibits thereto, and any other
documents in connection therewith, with the Securities and Exchange Commission,
and with any other entity when and if such is mandated by the Exchange Act or by
the By-laws of the Financial Industry Regulatory Authority, granting unto said
attorney-in-fact and agent full power and authority to do and perform each and
every act and thing requisite and necessary fully to all intents and purposes as
the undersigned might or could do in person thereby ratifying and confirming all
that said attorney-in-fact and agent, or his substitute or substitutes, may
lawfully do or cause to be done by virtue hereof.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorney-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of April 8, 2021.



                                          /s/ James Bylund
                                          --------------------------------------
                                          Name: James Bylund

</PRE>
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</HTML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
