<ARTICLE> 5
<LEGEND>
This schedule contains financial information extracted from the financial
statements for Repligen Corporation and is qualified in its entirety by
reference to such financial statements.
</LEGEND>
<MULTIPLIER> 1,000

                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          MAR-31-2000
<PERIOD-END>                               SEP-30-1999
<CASH>                                          10,913
<SECURITIES>                                         0
<RECEIVABLES>                                      513
<ALLOWANCES>                                      (25)
<INVENTORY>                                        495
<CURRENT-ASSETS>                                12,205
<PP&E>                                           1,714
<DEPRECIATION>                                 (1,019)
<TOTAL-ASSETS>                                  12,982
<CURRENT-LIABILITIES>                              518
<BONDS>                                              0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           219
<OTHER-SE>                                      12,245
<TOTAL-LIABILITY-AND-EQUITY>                    12,982
<SALES>                                            811
<TOTAL-REVENUES>                                 1,670
<CGS>                                              483
<TOTAL-COSTS>                                    2,898
<OTHER-EXPENSES>                                     0
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                                   0
<INCOME-PRETAX>                                      0
<INCOME-TAX>                                         0
<INCOME-CONTINUING>                                  0
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   (1,228)
<EPS-BASIC>                                      (.06)
<EPS-DILUTED>                                    (.06)