Repli Gen Repligen Corporation 41 Seyon Street Building #1, Suite 100 Waltham, Massachusetts 02453 Telephone: (781) 250-0111 Telefax: (781) 250-0115 Repligen Reports Third Quarter 2013 Financial Results - Product Revenue

Repligen Reports Third Quarter 2013 Financial Results

- Product Revenue Grows 10% for the Quarter -

- Net Income Grows 226% to $5.9 Million -

- Earnings Conference Call and Webcast Today at 9:00 a.m. EST -

WALTHAM, MA November 7, 2013 Repligen Corporation (NASDAQ:RGEN) today reported financial results for the third quarter ended

September 30, 2013. Below are the Company s financial and business highlights for the third quarter, financial guidance for the year and dial-in numbers for today s conference call.

Third Quarter 2013 Financial Highlights

Operating expenses for the three-month period ended September 30, 2013 were $10.8 million compared to $12.9 million for the same period in 2012, a

decrease of $2.1 million or 17%. This decrease was driven by across-the-board reductions in operating expenses during the third quarter of 2013 compared to the same period in 2012. Cost of product revenue decreased by $759,000 or 12% due to product

mix and improved process yields and capacity utilization. Research and development (R&D) expense decreased by $1.0 million or 41%; and sales, general and administrative (SG&A) expense decreased by $224,000 or 7%. The reductions in R&D

and SG&A expense were primarily due to lower spending on clinical development programs as a result of the Company s strategic realignment announced in August 2012 to focus on building its bioprocessing business.

Repligen Reports Third Quarter 2013 Financial Results

Year-to-Date Financial Summary

Bioprocessing product revenue for the nine-month period ended September 30, 2013 was $37.1 million compared to $32.1 million for the same period in 2012,

an increase of 16%. Total revenue for the nine-month period ended September 30, 2013 was $52.8 million compared to $43.5 million during the same period in 2012, an increase of 21%. Operating expenses for the nine-month period ended

September 30, 2013 were $35.1 million compared to $38.8 million for the same period in 2012, a decrease of $3.7 million or 10%. For the first nine months of 2013 compared to the same period in 2012, R&D expense decreased by $2.2 million or

27%, and SG&A expense decreased by $639,000 or 6%. Net income for the nine-month period ended September 30, 2013 was $12.8 million compared to $4.6 million for the same period in 2012. Earnings per diluted share for the nine-month period

ended September 30, 2013 were $0.40 compared to $0.15 for the same period in 2012.

Third Quarter Business Updates

Repligen Reports Third Quarter 2013 Financial Results

Financial Guidance for 2013

The Company is updating its financial guidance for fiscal year 2013. This guidance is based on expectations for our existing business and does not include the

impact on our revenue and expenses of potential out-licensing agreements for our remaining clinical assets, potential bioprocessing acquisitions or fluctuations in foreign currency exchange rates.

Repligen will host a conference call and

webcast today, November 7, at 9:00 a.m. EST, to discuss its third quarter 2013 financial results and corporate developments. The live call can be accessed by dialing (877) 415-3180 for domestic callers or (857) 244-7323 for

international callers. Dial-in participants must provide the passcode 31006698. Alternatively, an audio webcast will be accessible via the Investor 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 30270739.

About Repligen Corporation

Repligen Corporation

(NASDAQ:RGEN) is a life sciences company focused on the development, production and commercialization of high-value consumable products used in the process of manufacturing biological drugs. Our bioprocessing products are sold to major life sciences

and biopharmaceutical companies worldwide. We are a leading manufacturer of Protein A, a critical reagent used to separate and purify monoclonal antibody therapeutics. We also supply several growth factor products used to increase cell culture

productivity during the fermentation stage of drug manufacturing. In addition, we have developed and market our OPUS line of pre-packed plug-and-play chromatography columns, and

we provide test kits to ensure final product quality. Repligen s corporate headquarters are located in Waltham, MA (USA) and our manufacturing facilities are located in Waltham, MA and Lund, Sweden.

Repligen Reports Third Quarter 2013 Financial Results

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, constitute forward-looking statements, including, without limitation, express or implied statements or guidance regarding future financial performance and position, our strategic decision to focus on the growth of our bioprocessing

business, the future demand for our bioprocessing, growth factor and chromatography products, our expected launch of large-scale pre-packed chromatography columns and suitability for larger-scale manufacturing, plans and objectives for future

operations, optimization of manufacturing process and assurance of GMP compliance resulting from facility expansion, our ability to successfully negotiate and consummate partnering transactions for our clinical stage assets, the clinical success of

RG3039 and its further clinical development and our receipt of any future payments under the terms of our agreement with Pfizer, Pfizer s ability to terminate the license for convenience, plans and objectives for product development and

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

could and similar expressions. 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, including as a result of acquisition, commercialization or partnership opportunities; our ability to successfully negotiate and consummate development and

commercialization partnerships for our portfolio of clinical-stage 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; the impact of the expiration on December 31, 2013 of Bristol-Meyers Squibb royalty payments from U.S. sales of Orencia , the success of current and future collaborative or supply relationships, including our agreement with Pfizer; our ability to compete with larger, better financed bioprocessing, pharmaceutical

and biotechnology companies; our ability to successfully integrate Repligen Sweden AB, including achieving manufacturing efficiencies at Repligen Sweden AB; our ability to optimize manufacturing process; our compliance with all Food and Drug

Administration 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 Reports Third Quarter 2013 Financial Results

REPLIGEN CORPORATION

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