REPLIGEN CORP — Director's Dealing 2011

Mar 31, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: REPLIGEN CORP (RGEN)
CIK: 0000730272
Period of Report: 2011-03-30

Reporting Person: RUSCHE JAMES R (Senior Vice President)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-03-30	Common Stock	P	5000	$2.66	Acquired	5000	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-03-30	Stock Option (Right to Buy)	$2.66	D	20000	Disposed	2011-04-03	Common Stock (20000)	Direct
2011-03-30	Stock Option (Right to Buy)	$2.66	M	5000	Disposed	2011-04-03	Common Stock (5000)	Direct

Footnotes

F1: The option was cancelled by mutual agreement of the Rporting Person and the Issuer in advance of its scheduled expiration date. The Reporting Person received the difference between $3.70, the closing price of the ISsuer's Common Stock on the transaction date, and $2.66, the exercise price of the stock option, less any applicable withholding taxes.