Repligen Corporation 41 Seyon Street Building #1, Suite 100 Waltham, Massachusetts 02453 Telephone: (781) 250-0111 FOR IMMEDIATE RELEASE Telefax: (781) 250-0115 Repligen Reports Second Quarter 2013 Financial Results - Pr

Repligen Reports Second Quarter 2013 Financial Results

- Product Revenue Grows 12% for the Quarter on Record Bioprocessing Sales -

- Net Income Grows 189% to $4.5 Million -

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

August 1, 2013 Repligen Corporation (NASDAQ:RGEN) today reported financial results for the second quarter ended June 30, 2013. Below are the Company s financial and business highlights for the second quarter of 2013,

financial guidance for the year and dial-in numbers for today s conference call.

Second Quarter 2013 Financial Highlights

Operating expenses for the three-month period ended June 30, 2013 were $11.4 million compared to $14.2 million for the

same period in 2012, a decrease of $2.8 million or 20%. This decrease was driven by across-the-board reductions in operating expenses during the second quarter of 2013 compared to the same period in 2012. Cost of product revenue decreased by $2.0

million or 28%; research and development (R&D) expense (including therapeutic program related expense) decreased by $600,000 or 21%; and sales, general and administrative (SG&A) expense decreased by $294,000 or 9%. 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 Second Quarter 2013 Financial Results

Year-to-Date Financial Summary

Bioprocessing product revenue for the six-month period ended June 30, 2013 was $24.9 million compared to $21.0 million for the same period in 2012, an increase of 19%. Total revenue for the six-month

period ended June 30, 2013 was $34.0 million compared to $28.3 million during the same period in 2012, an increase of 20%. Operating expenses for the six-month period ended June 30, 2013 were $24.3 million compared to $25.9 million for the

same period in 2012, a decrease of $1.5 million or 6%. For the first six months of 2013 compared to the same period in 2012, R&D expense decreased by $1.2 million or 21%, and SG&A expense decreased by $415,000 or 6%. Net income for the

six-month period ended June 30, 2013 was $6.9 million compared to $2.8 million for the same period in 2012. Earnings per diluted share for the six-month period ended June 30, 2013 were $0.21 compared to $0.09 for the same period in 2012.

This is the Company s second quarterly reporting period for which both the current and preceding year periods reflect combined financial

results since the Company s acquisition of Novozymes Biopharma AB (now Repligen Sweden AB) in December 2011.

Strong demand for Protein A ligands and a substantial increase in sales of our OPUS pre-packed chromatography columns were key drivers in achieving record bioprocessing product sales during the second

quarter, said Walter C. Herlihy, Ph.D., President and CEO of Repligen. Product margin gains reflect the impact of cost reductions at Repligen Sweden AB as well as improved manufacturing capacity utilization tied to higher order volumes

and increased production.

Second Quarter Business Highlights

Repligen Reports Second 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 milestone payments from Pfizer, additional outlicensing 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, August 1, at 9:00 a.m. EDT, to discuss its second quarter 2013 financial results and corporate developments. The live call can be accessed by

dialing 877-280-4960 for domestic callers or 857-244-7317 for international callers. Dial-in participants must provide the passcode 52303386. 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 22671187.

Repligen Reports Second Quarter 2013 Financial Results

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. Aside from our core bioprocessing business, we have a portfolio of clinical-stage partnering assets, including a pancreatic imaging agent in Phase 3 development and an orphan drug candidate in Phase 1 development.

Repligen s corporate headquarters are located in Waltham, MA (USA) and our manufacturing facilities are located in Waltham, MA and Lund, Sweden.

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, plans and

objectives for future operations, our ability to successfully negotiate and consummate partnering transactions for our clinical stage assets, specifically RG1068 and RG2833, 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 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 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

Repligen Reports Second Quarter 2013 Financial Results

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Repligen Corporation

Repligen Reports Second Quarter 2013 Financial Results

REPLIGEN CORPORATION

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS)