Repligen Corporation 41 Seyon Street Building #1, Suite 100 Waltham, Massachusetts 02453 Repligen Reports First Quarter 2015 Financial Results - Product Sales Increase 45% to a Record $20.8 Million - - Conference Call an

Repligen Reports First Quarter 2015 Financial Results

- Product Sales Increase 45% to a Record $20.8 Million -

- Conference Call and Webcast Today at 8:30 a.m. EDT -

WALTHAM, MA May 7, 2015 Repligen Corporation (NASDAQ:RGEN) today reported financial results for the first quarter ended

March 31, 2015. Below are the Company s performance highlights for the quarter, followed by updated financial guidance for the year 2015 and access information for today s webcast and conference call.

First Quarter Financial Highlights

Operating expenses for the three-month period ended March 31, 2015 were $16.8 million compared to $11.0 million

for the same period in 2014, an increase of $5.8 million. The increase in operating expense included a $1.7 million increase in cost of product revenue associated with higher product sales, $1.1 million in contingent consideration expense based on

the high probability of achieving a 2015 sales milestone for the ATF System and a $2.6 million increase in sales, general and administrative (SG&A) expense. The increase in SG&A expense is due primarily to costs related to the expansion of

staff and facilities and a $1.2 million increase related to professional fees and systems implementation to support the integration of the ATF System, which Repligen acquired from Refine Technology, LLC in June 2014.

Tony J. Hunt, Chief Operating Officer and designated President and CEO of Repligen said, 2015 is off to a strong start, with first quarter revenue gains

across all of our product groups and particular strength in our affinity ligand and growth factor businesses. Our gross margin expansion was driven by increased capacity utilization in our plants. As anticipated, we launched our OPUS 60 cm diameter pre-packed chromatography columns at the end of March, and we have two additional product launches planned for this year. With a larger commercial organization now in place, we are

focused on expanding our customer base, building our brand and increasing the market penetration of our proprietary products.

retiring President and Chief Executive Officer said, Our first quarter results are indicative of the Company s potential to deliver strong organic growth and achieve outstanding operating performance in the Life Sciences sector. I am

confident that the combination of sustained investment in new product development and additional strategic acquisitions will enable Repligen to continue to deliver value for our customers and our shareholders.

Financial Guidance for 2015

Based on our first quarter

results and expectations for the remainder of 2015, we are revising our financial guidance as summarized below. This guidance for the year 2015 is based on expectations for our existing business and does not include the impact on our revenue and

expenses of potential milestone payments from BioMarin, the financial impact of potential bioprocessing acquisitions or future fluctuations in foreign currency exchange rates.

First Quarter 2015 Business Highlights

Repligen will host a conference call and

webcast today, May 7, 2015 at 8:30 a.m. EDT, to discuss first quarter 2015 financial results and business updates. The live call can be accessed by dialing toll-free (844) 835-7432 for domestic callers or (404) 537-3372 for

international callers. Dial-in participants must provide the passcode 34417361. In addition, a webcast will be accessible via the Investor Relations section of Repligen s website www.repligen.com; see Events & Presentations. Both the

conference call and webcast will be archived for a period of time following the live event. The replay dial-in numbers are (855) 859-2056 for domestic callers and (404) 537-3406 for international callers. Replay listeners must provide the

Non-GAAP Financial Measures

this release, the Company is reporting earnings before interest, taxes, depreciation and amortization (EBITDA). EBITDA is a non-GAAP financial measure and should not be viewed as an alternative to GAAP measures of performance. The Company has

provided a reconciliation of GAAP net income to EBITDA at the end of this release. The Company believes that the use of this non-GAAP measure better enables management and investors to benchmark its results against historical performance and the

performance of peers, and to evaluate acquisition and other investment opportunities.

About Repligen Corporation

Repligen Corporation (NASDAQ:RGEN) is a life sciences company focused on the development 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 the leading manufacturer of Protein A affinity ligands, a critical component of Protein A media

that is used to separate and purify monoclonal antibody therapeutics. Our ATF System and our growth factor products are used to increase product yield during the fermentation stage of biologic drug manufacturing. In addition, we developed and market

an innovative line of ready-to-use chromatography columns under our OPUS brand that we deliver pre-packed with our customers choice of purification media. Repligen s

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

constitutes a Safe Harbor statement under the Private Securities Litigation Reform Act of 1995: 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, including cash and investment position, the future demand for our bioprocessing products, objectives for future

operations, our receipt of any future payments under the terms of our agreement with BioMarin, our contingent payment obligations under the terms of our agreement with Refine, 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 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 success of current and future collaborative or supply relationships, including our agreement with BioMarin; our ability to compete

with larger, better financed bioprocessing, pharmaceutical and biotechnology companies; our ability to successfully integrate the ATF business; our ability to optimize manufacturing process; our compliance with all Food and Drug Administration and

EMEA regulations; 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.

Senior Director Investor Relations

Repligen Corporation

REPLIGEN CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

REPLIGEN CORPORATION

RECONCILIATION OF GAAP NET INCOME TO NON-GAAP EBITDA