Repligen Corporation 41 Seyon Street Building #1, Suite 100 Waltham, Massachusetts 02453 Telephone: 781-250-0111 FOR IMMEDIATE RELEASE Telefax: 781-250-0115 Repligen Announces Strategic Focus on Bioprocessing Business an

Repligen Announces Strategic Focus on Bioprocessing Business and

Reports Second Quarter 2012 Financial Results

Reports 168% Increase in Bioprocessing Product Sales

Raises Revenue Guidance for 2012

WALTHAM, MA August 2, 2012 Repligen Corporation (NASDAQ: RGEN) today reported financial results for its second quarter and year-to-date period ended June 30, 2012. In

addition, the Company announced that it will focus its corporate strategy and resources on the growth of its core bioprocessing business, which achieved record sales during the quarter. As a result of this defined strategic focus, the Company will

seek a development and commercialization partner for its pancreatic imaging product candidate, RG1068.

reported total revenue for the three-month period ended June 30, 2012 of $15,524,000 compared to $7,654,000 for the same period in 2011. Revenue growth for the second quarter of 2012 was driven by the Company s expanded bioprocessing

business, which generated $11,659,000 in product revenue compared to $4,358,000 for the same period in 2011, an increase of 168%. Royalty and research revenue for the three-month period ended June 30, 2012, consisting primarily of royalty

payments from Bristol-Myers Squibb on its U.S. sales of Orencia , was $3,865,000 compared to $3,295,000 for the

same period in 2011. June 30, 2012 marks the end of the second fiscal quarter for which the Company is reporting consolidated financial results since its acquisition of Novozymes Biopharma Sweden AB (now Repligen Sweden AB) in December

Our strong second quarter and year-to-date financial performance was highlighted by revenue gains in our recently expanded

bioprocessing business, said Walter C. Herlihy, Ph.D., President and CEO of Repligen. The successful integration of Repligen Sweden, our longstanding expertise in bioprocessing product development and manufacturing, and the continued

strength in the global market for biologic drugs were key factors in our decision to focus corporate strategy and resources on bioprocessing. We are committed to building Repligen into a sustainably profitable, best-in-class life sciences company

focused on providing high-value consumables used to manufacture biologics.

Operating expenses for the three-month period ended

June 30, 2012 were $14,206,000 compared to $7,775,000 for the same period in 2011, an increase of $6,431,000 or 83%. These operating expenses included an increase in cost of product revenue of $5,792,000 due to higher sales, and an increase in

selling, general and administrative expenses of $1,129,000 compared to the same three-month period in 2011. These increases were primarily due to the addition of Repligen Sweden AB in December 2011. In addition, research and development expenses

decreased by $612,000 during the three-month period ended June 30, 2012 compared to the same period in 2011. Expenses for the second quarter included $511,000 for employee salary and severance associated with our cost reduction initiatives at

Repligen Sweden. Net income for the three-month period ended June 30, 2012 was $1,570,000 or

Repligen Announces Strategic Focus on Bioprocessing Business and Reports Second Quarter 2012

$0.05 per diluted share, compared to a net loss of $56,000 or $0.00 per diluted share for the same period in 2011. Cash and investments as of June 30, 2012 were $39,232,000 compared to

$36,025,000 as of December 31, 2011.

For the six-month period ended June 30, 2012, total revenue was $28,348,000 compared to total

revenue of $13,560,000 for the same period in 2011. Operating expenses for the six-month period ended June 30, 2012 were $25,863,000 compared to $15,768,000 for the same period in 2011. Net income for the six-month period ended June 30,

2012 was $2,796,000 or $0.09 per diluted share compared to a net loss of $2,086,000 or $0.07 per diluted share for the same period in 2011.

Based on current sales projections, the Company is raising revenue guidance for fiscal year 2012 from its previous estimate of $52 million to $55 million

to its current estimate of $55 million to $57 million. Included in this total revenue estimate is bioprocessing revenue, for which the Company is increasing its previous estimate of $39 million to $41 million to its current estimate of $41 million

to $43 million. The Company is also adjusting its estimate for net profit to $5 million to $7 million for fiscal year 2012; an increase based in part on anticipated reductions in research and development costs associated with its diagnostic and

Repligen corporate events for the year-to-date included the following:

Repligen Announces Strategic Focus on Bioprocessing Business and Reports Second Quarter 2012

Repligen will host a conference call and webcast today, August 2, 2012, at 8:30 a.m. EDT, to discuss second quarter 2012 financial results, corporate

developments for the year to date and other business matters. The live call can be accessed by dialing (866) 543-6407 for domestic callers or (617) 213-8898 for international callers. Dial-in participants must provide the

passcode 51406171. The webcast can be accessed at the Investors section of Repligen s website www.repligen.com. Both the conference call and webcast will be archived for a period of time following the live event. The replay

dial-in numbers are (888) 286-8010 for domestic callers and (617) 801-6888 for international callers. Replay listeners must provide the passcode 79641908.

Repligen Announces Strategic Focus on Bioprocessing Business and Reports Second Quarter 2012

About Repligen Corporation

Repligen Corporation is a life sciences company that develops, manufactures and markets bioprocessing products for life sciences and biopharmaceutical manufacturing customers worldwide. We are a leading

manufacturer of both native and recombinant forms of Protein A, critical reagents used in the manufacture of monoclonal antibodies, a type of biologic drug. We also supply several growth factor products used to increase cell culture productivity

during the biomanufacturing process. In the burgeoning area of disposable biomanufacturing technologies, we have developed and market a series of OPUS (Open Platform User Specified) single-use chromatography columns used in the purification

process for clinical-stage biologics. In addition to our core bioprocessing business, Repligen has a portfolio of clinical-stage partnering assets that includes two central nervous system (CNS) orphan drug candidates and a pancreatic imaging agent

in Phase 3 development. Repligen s corporate headquarters are located at 41 Seyon Street, Building #1, Suite 100, Waltham, MA 02453. Additional information can be found at www.repligen.com.

This press release contains forward-looking statements, which are made pursuant to the safe harbor provisions of Section 27A of the Securities

Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Investors are cautioned that statements in this press release which are not strictly historical statements, including, without limitation, express or

implied statements regarding future financial performance and position, our strategic decision to focus on the growth of our bioprocessing business, the FDA and EMA review of our NDA and MAA for RG1068 (SecreFlo ) and additional clinical data

that may be required in connection therewith, plans and objectives for future operations, our ability to successfully negotiate and consummate partnering transactions for our clinical stage assets, including RG1068, RG3039 and RG2833, plans and

objectives for product development, our market share and product sales and other statements identified by words like believe, expect, may, will, should, seek, or

could and similar expressions, constitute forward-looking statements. Such forward-looking statements are subject to a number of risks and uncertainties that could cause actual results to differ materially from those anticipated,

including, without limitation, risks associated with: our ability to successfully grow our bioprocessing business; our ability to successfully negotiate and consummate development and commercialization partnerships for our portfolio of therapeutic

and diagnostic assets on acceptable terms, if at all; our ability to develop and commercialize products and the market acceptance of our products; reduced demand for our products that adversely impacts our future revenues, cash flows, results of

operations and financial condition; our ability to obtain regulatory approvals; the success of current and future collaborative or supply relationships; our ability to compete with larger, better financed bioprocessing, pharmaceutical and

biotechnology companies; our ability to successfully integrate Repligen Sweden AB; the success of our clinical trials; new approaches to the treatment of our targeted diseases; our compliance with all FDA and EMEA regulations; our ability to obtain,

maintain and protect intellectual property rights for our products; the risk of litigation regarding our intellectual property rights; our limited sales capabilities; our volatile stock price; and other risks detailed in Repligen s Annual

Report on Form 10-K on file with the Securities and Exchange Commission and the other reports that Repligen periodically files with the Securities and Exchange Commission. Actual results may differ materially from those Repligen contemplated by

these forward-looking statements. These forward looking statements reflect management s current views and Repligen does not undertake to update any of these forward-looking statements to reflect a change in its views or events or circumstances

that occur after the date hereof except as required by law.

Director Investor Relations

Repligen Corporation

Repligen Announces Strategic Focus on Bioprocessing Business and Reports Second Quarter 2012

REPLIGEN CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)