<ACCESSION-NUMBER>0001193125-19-152725 <TYPE>8-K <PUBLIC-DOCUMENT-COUNT>1 <PERIOD>20190515 <ITEMS>5.07 <FILING-DATE>20190521 <DATE-OF-FILING-DATE-CHANGE>20190521 <FILER> <COMPANY-DATA> <CONFORMED-NAME>REPLIGEN CORP <CIK>0000730272 <ASSIGNED-SIC>2836 <IRS-NUMBER>042729386 <STATE-OF-INCORPORATION>DE <FISCAL-YEAR-END>1231 </COMPANY-DATA> <FILING-VALUES> <FORM-TYPE>8-K <ACT>34 <FILE-NUMBER>000-14656 <FILM-NUMBER>19842526 </FILING-VALUES> <BUSINESS-ADDRESS> <STREET1>41 SEYON STREET <STREET2>BUILDING 1, SUITE 100 <CITY>WALTHAM <STATE>MA <ZIP>02453 <PHONE>7814499560 </BUSINESS-ADDRESS> <MAIL-ADDRESS> <STREET1>41 SEYON STREET <STREET2>BUILDING 1, SUITE 100 <CITY>WALTHAM <STATE>MA <ZIP>02453 </MAIL-ADDRESS> </FILER>