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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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<SEC-DOCUMENT>0001193125-09-021357.txt : 20090206
<SEC-HEADER>0001193125-09-021357.hdr.sgml : 20090206
<ACCEPTANCE-DATETIME>20090206165838
ACCESSION NUMBER:		0001193125-09-021357
CONFORMED SUBMISSION TYPE:	S-8
PUBLIC DOCUMENT COUNT:		3
FILED AS OF DATE:		20090206
DATE AS OF CHANGE:		20090206
EFFECTIVENESS DATE:		20090206

FILER:

	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:			0331

	FILING VALUES:
		FORM TYPE:		S-8
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-157168
		FILM NUMBER:		09577941

	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>S-8
<SEQUENCE>1
<FILENAME>ds8.htm
<DESCRIPTION>FORM S-8
<TEXT>
<HTML><HEAD>
<TITLE>Form S-8</TITLE>
</HEAD>
 <BODY BGCOLOR="WHITE">

 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>As filed with the Securities and Exchange Commission on February&nbsp;6, 2009 </B></FONT></P> <P
STYLE="margin-top:0px;margin-bottom:0px" ALIGN="right"><FONT FACE="Times New Roman" SIZE="2"><B>Registration No.&nbsp;333-<U>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</U> </B></FONT></P> <P
STYLE="line-height:0px;margin-top:0px;margin-bottom:0px;border-bottom:0.5pt solid #000000">&nbsp;</P> <P STYLE="line-height:3px;margin-top:0px;margin-bottom:2px;border-bottom:0.5pt solid #000000">&nbsp;</P> <P
STYLE="margin-top:3px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="5"><B>UNITED STATES </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="5"><B>SECURITIES AND
EXCHANGE COMMISSION </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="3"><B>WASHINGTON, D.C.&nbsp;20549 </B></FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12px;margin-bottom:0px"
ALIGN="center"><FONT FACE="Times New Roman" SIZE="5"><B>FORM&nbsp;S-8 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="5"><B>REGISTRATION STATEMENT UNDER </B></FONT></P> <P
STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>THE </I></B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>SECURITIES ACT OF 1933
</I></B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P
STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="6"><B>REPLIGEN CORPORATION </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B><I>(Exact Name
of Registrant as Specified in Its Charter) </I></B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P
STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" ALIGN="center">

<TR>
<TD WIDTH="50%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="49%"></TD></TR>
<TR>
<TD VALIGN="top" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>Delaware</B></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>04-2729386</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>(State of Incorporation)</B></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>(I.R.S. Employer Identification No.)</B></FONT></TD></TR>
</TABLE> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>41 Seyon Street </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
FACE="Times New Roman" SIZE="2"><B>Building #1, Suite 100 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>Waltham, MA 02453 </B></FONT></P> <P
STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>(781) 250-0111 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B><I>(Address of
Registrant&#146;s principal executive offices) </I></B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P
STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>SECOND AMENDED AND RESTATED
2001 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>REPLIGEN CORPORATION STOCK PLAN </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
FACE="Times New Roman" SIZE="1"><B><I>(Full Title of the Plan) </I></B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P
STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>Walter C. Herlihy, Ph.D. </B>
</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>President and Chief Executive Officer </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
FACE="Times New Roman" SIZE="2"><B>Repligen Corporation </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>41 Seyon Street </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"
ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>Building #1, Suite 100 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>Waltham, MA 02453 </B></FONT></P> <P
STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>(781) 250-0111 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B><I>(Name, address,
including zip code, and telephone number, including area code, of agent for service) </I></B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P
STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B><I>With copy to: </I></B>
</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>Robert E. Puopolo,&nbsp;Esq. </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman"
SIZE="2"><B>Goodwin Procter LLP </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>Exchange Place </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
FACE="Times New Roman" SIZE="2"><B>Boston, Massachusetts 02109-2881 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>(617) 570-1000 </B></FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
FACE="Times New Roman" SIZE="2">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of &#147;large accelerated filer,&#148;
&#147;accelerated filer&#148; and &#147;smaller reporting company&#148; in Rule 12b-2 of the Exchange Act. </FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" ALIGN="center">

<TR>
<TD WIDTH="16%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="60%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="20%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="1%"></TD></TR>
<TR>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Large&nbsp;accelerated&nbsp;filer</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2"><FONT FACE="WINGDINGS">&#168;</FONT></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Accelerated&nbsp;filer</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2"><FONT FACE="WINGDINGS">&#120;</FONT></FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Non-accelerated filer</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2"><FONT FACE="WINGDINGS">&#168;</FONT>&nbsp;&nbsp;(Do not check if a smaller reporting company)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Smaller&nbsp;reporting&nbsp;company</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2"><FONT FACE="WINGDINGS">&#168;</FONT></FONT></TD></TR>
</TABLE> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P
STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>Calculation of Registration
Fee </B></FONT></P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" ALIGN="center">

<TR>
<TD WIDTH="44%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="13%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="13%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="13%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="13%"></TD></TR>
<TR STYLE="font-size:1px">
<TD COLSPAN="9" VALIGN="bottom" STYLE="border-top:1px solid #000000">&nbsp;</TD></TR>
<TR>
<TD VALIGN="bottom" ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="1"><B>Title of Securities to be Registered</B></FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Amount</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"
ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>to be<BR>Registered(2)(3)</B></FONT></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Proposed</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"
ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Maximum</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Offering Price</B></FONT></P> <P
STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Per Share(4)</B></FONT></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Proposed</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"
ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Maximum<BR>Aggregate</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Offering Price(4)</B></FONT></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="1"><B>Amount of<BR>Registration Fee</B></FONT></TD></TR>
<TR>
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">Common Stock, par value $0.01 per share(1)</FONT></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">41,091 shares</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$5.39(6)</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$221,481(6)</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD></TR>
<TR>
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">55,500 shares</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$4.46(6)</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$247,530(6)</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD></TR>
<TR>
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">6,000 shares</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$3.75(6)</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$22,500(6)</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD></TR>
<TR>
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">897,409&nbsp;shares</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$4.11</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$3,688,351</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD></TR>
<TR>
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">Totals</FONT></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">1,000,000&nbsp;shares&nbsp;(5)</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$4,179,862</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">$165.</FONT></TD></TR>
<TR STYLE="font-size:1px">
<TD COLSPAN="9" VALIGN="bottom" STYLE="border-top:1px solid #000000">&nbsp;</TD></TR>
<TR STYLE="font-size:1px">
<TD COLSPAN="9" VALIGN="bottom" STYLE="border-top:1px solid #000000">&nbsp;</TD></TR>
</TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2">(1)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">This Registration Statement also relates to the Rights to purchase shares of Series A Junior Participating Preferred Stock of the Registrant which are attached to all shares of
Common Stock pursuant to the terms of the Registrant&#146;s Rights Agreement dated March&nbsp;3, 2003. Until the occurrence of certain prescribed events, the Rights are not exercisable, are evidenced by the certificates for the Common Stock and will
be transferred only with such stock. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2">(2)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">This Registration Statement relates to 1,000,000 shares of Common Stock, par value $0.01 per share, of Repligen Corporation. (&#147;Common Stock&#148;) available for issuance under
the Second Amended and Restated 2001 Repligen Corporation Stock Plan (together with previous versions of such plan, the &#147;Plan&#148;); plus such indeterminate number of additional shares of Common Stock as may be required pursuant to the Plan in
the event of a stock dividend, stock split, recapitalization or other similar event. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2">(3)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Repligen Corporation (the &#147;Company&#148;) previously filed a registration statement on Form S-8 on May&nbsp;24, 2002 registering the issuance of shares of Common Stock under
the Plan. By filing this Registration Statement in accordance with Instruction E to Form S-8, the Company registers the issuance of the 1,000,000 additional shares of Common Stock approved for issuance under the Plan at the Annual Meeting of
Stockholders of the Company held on September&nbsp;12, 2008. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2">(4)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">This estimate is made pursuant to Rule 457(c) and (h)&nbsp;under the Securities Act of 1933, as amended (the &#147;Securities Act&#148;), solely for the purpose of determining the
amount of the registration fee. The registration fee is based upon the average of the high and low sales prices for a share of Common Stock on February&nbsp;2, 2009, as reported on the NASDAQ Global Market. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2"><B>(5)</B></FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2"><B></B>Pursuant to Rule 416(c) under the Securities Act of 1933, this registration statement shall also be deemed to cover an indeterminate number of additional shares of Common
Stock issuable in the event the number of outstanding shares of the Company is increased by split-up, reclassification, stock dividend, recapitalization, and certain other capital adjustments and the like<B>.</B> </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2"><B>(6)</B></FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2"><B></B>Such shares are issuable upon the exercise of outstanding options with fixed exercise prices. Pursuant to Rule 457(h), the aggregate offering price and fee have been computed
upon the basis of the price at which such options may be exercised. The offering price per share set forth for such shares is the exercise price per share at which such options are exercisable. </FONT></TD></TR></TABLE> <P
STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P> <P STYLE="line-height:3px;margin-top:0px;margin-bottom:0px;border-bottom:0.5pt solid #000000">&nbsp;</P> <P
STYLE="line-height:3px;margin-top:0px;margin-bottom:2px;border-bottom:0.5pt solid #000000">&nbsp;</P>

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<HR  SIZE="3" COLOR="#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">The Company previously filed a Registration Statement on Form S-8 with the Securities and Exchange
Commission on May&nbsp;24, 2002 (SEC File No.&nbsp;333-84140) in connection with the Plan (the &#147;Original Filing&#148;). This Registration Statement registers additional shares of the Company&#146;s Common Stock to be issued pursuant to the
Plan. The contents of the Original Filing are incorporated by reference into this Registration Statement pursuant to General Instruction E of Form S-8. </FONT></P> <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT
FACE="Times New Roman" SIZE="2"><B>PART I </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS </B></FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2"><B>Item&nbsp;1.</B></FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2"><B>Plan Information* </B></FONT></TD></TR></TABLE> <P STYLE="font-size:18px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2"><B>Item&nbsp;2.</B></FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2"><B>Registrant Information and Employee Plan Annual Information* </B></FONT></TD></TR></TABLE> <P STYLE="margin-top:6px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">*The
documents containing the information specified in this Part I will be sent or given to employees, directors or others as specified by Rule 428(b)(1) of the Securities Act of 1933, as amended (the &#147;<U>Securities Act</U>&#148;). In accordance
with the rules and regulations of the Securities and Exchange Commission (the &#147;<U>Commission</U>&#148;) and the Introductory Note to Part I of Form S-8, such documents are not being filed with the Commission either as part of this Registration
Statement or as prospectuses or prospectus supplements pursuant to Rule 424. </FONT></P> <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>PART II </B></FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>INFORMATION REQUIRED IN THE REGISTRATION STATEMENT </B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2"><B>Item&nbsp;8.</B></FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2"><B>Exhibits </B></FONT></TD></TR></TABLE> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">The exhibits listed below represent a
complete list of exhibits filed or incorporated by reference as part of this Registration Statement. </FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="92%" BORDER="0" ALIGN="center">

<TR>
<TD WIDTH="5%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="93%"></TD></TR>
<TR>
<TD VALIGN="bottom" NOWRAP> <P STYLE="border-bottom:1px solid #000000;width:28pt"><FONT FACE="Times New Roman" SIZE="1"><B>Exhibit<BR>Number</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="1"><B>Description</B></FONT></P></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.1</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Amended and Restated By-laws (filed as Exhibit&nbsp;3.2 to Repligen Corporation&#146;s Quarterly Report on Form 10-Q for the quarter ended September 30, 2003 and incorporated herein by
reference) (SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.2</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Restated Certificate of Incorporation dated June 30, 1992 and amended September 17, 1999 (filed as Exhibit 3.1 to Repligen Corporation&#146;s Quarterly Report on Form 10-Q for the quarter ended
September 30, 1999 and incorporated herein by reference) (SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.3</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Certificate of Designation of Series A Junior Participating Preferred Stock dated March 4, 2003 (filed as Exhibit A of Exhibit 1 to Repligen Corporation&#146;s Registration Statement on Form 8-A
filed March 4, 2003 and incorporated herein by reference) (SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.4</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Specimen Stock Certificate (filed as Exhibit&nbsp;4.1 to Repligen Corporation&#146;s Annual Report on Form&nbsp;10-K for the year ended March&nbsp;31, 2002 and incorporated herein by reference)
(SEC File No. 000-14656).</FONT></TD></TR>
</TABLE>

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<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="92%" BORDER="0" ALIGN="center">

<TR>
<TD WIDTH="4%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="94%"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.5</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Rights Agreement, dated as of March&nbsp;3, 2003, between Repligen Corporation and American Stock Transfer &amp; Trust Company (filed as Exhibit 4.1 to Repligen Corporation&#146;s Current Report
on Form 8-K filed March&nbsp;4, 2003 and incorporated herein by reference) (SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;*5.1</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Legal opinion from Goodwin Procter <SMALL>LLP</SMALL></FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">*23.1</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Consent of Ernst &amp; Young LLP, as independent registered public accounting firm</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;23.2</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Consent of Goodwin Procter <SMALL>LLP</SMALL> (contained in the opinion filed as Exhibit 5.1 to this Registration Statement)</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;24.1</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Power of attorney (included on the signature page to this Registration Statement)</FONT></TD></TR>
</TABLE>
<TABLE WIDTH="12%">
<TR>
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="8%"><HR SIZE="1" NOSHADE COLOR="#000000" ALIGN="left"></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2">*</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Filed herewith. </FONT></TD></TR></TABLE>

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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>SIGNATURES </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
FACE="Times New Roman" SIZE="2">Pursuant to the requirements of the Securities Act of 1933, as amended, the Company certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused
this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Waltham, Massachusetts, on this 6th day of February, 2009. </FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><DIV
ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0">

<TR>
<TD WIDTH="6%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="92%"></TD></TR>
<TR>
<TD VALIGN="top" COLSPAN="3"><FONT FACE="Times New Roman" SIZE="2">REPLIGEN CORPORATION</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:1px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Walter C. Herlihy, Ph.D.</FONT></P></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2">Walter C. Herlihy, Ph.D.</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT FACE="Times New Roman" SIZE="2"><I>President and Chief Executive Officer</I></FONT></TD></TR>
</TABLE></DIV> <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>POWER OF ATTORNEY </B></FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">KNOW ALL BY THESE PRESENTS that each individual whose signature appears below constitutes and appoints each of Walter C. Herlihy, Ph.D. and William Kelly
as such person&#146;s true and lawful attorney-in-fact and agent with full power of substitution and resubstitution, for such person in such person&#146;s name, place and stead, in any and all capacities, to sign any and all amendments (including
post-effective amendments) to this Registration Statement (or any Registration Statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933), and to file the same, with all exhibits
thereto, and all documents in connection therewith, with the Securities and Exchange Commission, granting unto each said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be
done in and about the premises, as fully to all intents and purposes as such person might or could do in person, hereby ratifying and confirming all that any said attorney-in-fact and agent, or any substitute or substitutes of any of them, may
lawfully do or cause to be done by virtue hereof. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">Pursuant to the requirements of the Securities Act of 1933, this Registration Statement
has been signed by the following persons in the capacities and on the date indicated. Each person listed below has signed this Registration Statement as an officer or director of Repligen Corporation. </FONT></P>

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<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" ALIGN="center">

<TR>
<TD WIDTH="35%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="32%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="29%"></TD></TR>
<TR>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Signature</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Title</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="1"><B>Date</B></FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Walter C. Herlihy, Ph.D.</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman"
SIZE="2">Walter C. Herlihy, Ph.D.</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">President, Chief Executive Officer and Director (Principal Executive Officer)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">February 6, 2009</FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:1px">&nbsp;</P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ William Kelly</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman"
SIZE="2">William Kelly</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Chief Financial Officer (Principal Financial Officer and Principal Accounting Officer)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">February 6, 2009</FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:1px">&nbsp;</P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Karen Dawes</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="2">Karen
Dawes</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Director</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">February 6, 2009</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Earl Webb Henry, M.D.</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman"
SIZE="2">Earl Webb Henry, M.D.</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Director</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">February 6, 2009</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Alfred L. Goldberg, Ph.D.</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman"
SIZE="2">Alfred L. Goldberg, Ph.D.</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Director</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">February 6, 2009</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Alexander Rich, M.D.</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman"
SIZE="2">Alexander Rich, M.D.</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Director</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">February 6, 2009</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="bottom"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000"><FONT FACE="Times New Roman" SIZE="2">/s/ Thomas F. Ryan, Jr.</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman"
SIZE="2">Thomas F. Ryan, Jr.</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Director</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">February 6, 2009</FONT></TD></TR>
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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT FACE="Times New Roman" SIZE="2"><B>EXHIBIT INDEX </B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
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<TD VALIGN="bottom" NOWRAP> <P STYLE="border-bottom:1px solid #000000;width:28pt"><FONT FACE="Times New Roman" SIZE="1"><B>Exhibit<BR>Number</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT FACE="Times New Roman" SIZE="1"><B>Description</B></FONT></P></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.1</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Amended and Restated By-laws (filed as Exhibit&nbsp;3.2 to Repligen Corporation&#146;s Quarterly Report on Form 10-Q for the quarter ended September 30, 2003 and incorporated herein by
reference) (SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.2</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Restated Certificate of Incorporation dated June 30, 1992 and amended September 17, 1999 (filed as Exhibit 3.1 to Repligen Corporation&#146;s Quarterly Report on Form 10-Q for the quarter ended
September 30, 1999 and incorporated herein by reference) (SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.3</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Certificate of Designation of Series A Junior Participating Preferred Stock dated March 4, 2003 (filed as Exhibit A of Exhibit 1 to Repligen Corporation&#146;s Registration Statement on Form 8-A
filed March 4, 2003 and incorporated herein by reference) (SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.4</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Specimen Stock Certificate (filed as Exhibit&nbsp;4.1 to Repligen Corporation&#146;s Annual Report on Form&nbsp;10-K for the year ended March&nbsp;31, 2002 and incorporated herein by reference)
(SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;4.5</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Rights Agreement, dated as of March 3, 2003, between Repligen Corporation and American Stock Transfer &amp; Trust Company (filed as Exhibit 4.1 to Repligen Corporation&#146;s Current Report on
Form 8-K filed March 4, 2003 and incorporated herein by reference) (SEC File No. 000-14656).</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;*5.1</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Legal opinion from Goodwin Procter <SMALL>LLP</SMALL></FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">*23.1</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Consent of Ernst &amp; Young LLP, as independent registered public accounting firm</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;23.2</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Consent of Goodwin Procter <SMALL>LLP</SMALL> (contained in the opinion filed as Exhibit 5.1 to this Registration Statement)</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT FACE="Times New Roman" SIZE="2">&nbsp;&nbsp;24.1</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Power of attorney (included on the signature page to this Registration Statement)</FONT></TD></TR>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2">*</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Filed herewith. </FONT></TD></TR></TABLE>
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</DOCUMENT>
<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>dex51.htm
<DESCRIPTION>LEGAL OPINION FROM GOODWIN PROCTER LLP
<TEXT>
<HTML><HEAD>
<TITLE>Legal opinion from Goodwin Procter LLP</TITLE>
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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="right"><FONT FACE="Times New Roman" SIZE="2"><B><U>Exhibit 5.1 </U></B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; margin-left:56%"
ALIGN="center"><FONT FACE="Times New Roman" SIZE="2">February&nbsp;6, 2009 </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Repligen Corporation </FONT></P> <P
STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">41 Seyon Street, </FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Building #1, Suite 100 </FONT></P> <P
STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Waltham, Massachusetts&nbsp;02453 </FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
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<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT FACE="Times New Roman" SIZE="2">Re:</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT FACE="Times New Roman" SIZE="2"><U>Securities Being Registered under Registration Statement on Form S-8</U> </FONT></TD></TR></TABLE> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman"
SIZE="2">Ladies and Gentlemen: </FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">This opinion letter is furnished to you in connection with your filing of a Registration Statement on Form
S-8 (the &#147;Registration Statement&#148;) pursuant to the Securities Act of 1933, as amended (the &#147;Securities Act&#148;), on or about the date hereof relating to an aggregate of 1,000,000 shares (the &#147;Shares&#148;) of Common Stock,
$0.01 par value per share, of Repligen Corporation, a Delaware corporation (the &#147;Company&#148;), that may be issued pursuant to the Second Amended and Restate 2001 Stock Option and Incentive Plan (the &#147;Plan&#148;). </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">We have reviewed such documents and made such examination of law as we have deemed appropriate to give the opinions expressed below.&nbsp;We have relied,
without independent verification, on certificates of public officials and, as to matters of fact material to the opinion set forth below, on certificates of officers of the Company. </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">The opinion expressed below is limited to the Delaware General Corporation Law (which includes applicable provisions of the Delaware Constitution and
reported judicial decisions interpreting the Delaware General Corporation Law and the Delaware Constitution). </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">For purposes of the opinion
expressed below, we have assumed that a sufficient number of authorized but unissued shares of the Company&#146;s Common Stock will be available for issuance when the Shares are issued. </FONT></P> <P
STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">Based on the foregoing, we are of the opinion that the Shares have been duly authorized and, upon issuance and delivery against payment therefore in
accordance with the terms of the Plan, will be validly issued, fully paid and nonassessable. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT FACE="Times New Roman" SIZE="2">We hereby consent to the inclusion of this
opinion as Exhibit 5.1 to the Registration Statement.&nbsp;In giving our consent, we do not admit that we are in the category of persons whose consent is required under Section&nbsp;7 of the Securities Act or the rules and regulations thereunder.
</FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><DIV ALIGN="right">
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<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">Very truly yours,</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">/s/ Goodwin Procter, LLP</FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD></TR>
<TR>
<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">GOODWIN PROCTER LLP</FONT></TD></TR>
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<DOCUMENT>
<TYPE>EX-23.1
<SEQUENCE>3
<FILENAME>dex231.htm
<DESCRIPTION>CONSENT OF ERNST & YOUNG LLP
<TEXT>
<HTML><HEAD>
<TITLE>Consent of Ernst &amp; Young LLP</TITLE>
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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="right"><FONT FACE="Times New Roman" SIZE="2"><B><U>Exhibit 23.1 </U></B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT
FACE="Times New Roman" SIZE="2"><B>Consent of Independent Registered Public Accounting Firm </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">We consent to the incorporation by reference in the
Registration Statement (Form S-8) pertaining to the Second Amended and Restated 2001 Repligen Corporation Stock Plan of Repligen Corporation of our reports dated June&nbsp;11, 2008, with respect to the financial statements of Repligen Corporation,
included in its Annual Report (Form 10-K) for the year ended March&nbsp;31, 2008 and the effectiveness of internal control over financial reporting of Repligen Corporation, filed with the Securities and Exchange Commission. </FONT></P> <P
STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><DIV ALIGN="right">
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<TD VALIGN="top"><FONT FACE="Times New Roman" SIZE="2">/s/ Ernst &amp; Young LLP</FONT></TD></TR>
</TABLE></DIV> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT FACE="Times New Roman" SIZE="2">Boston, Massachusetts </FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT FACE="Times New Roman"
SIZE="2">February&nbsp;4, 2009 </FONT></P>
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