Dyax Amends Loan Agreement with HealthCare Royalty Partners for an Additional $15 Million

Cambridge, MA, March 18, 2009 – Dyax Corp. (NASDAQ: DYAX) announced today that it has amended its existing loan agreement with HealthCare Royalty Partners, L.P. (“HC Royalty”) to receive an additional loan of $15 million (the “Tranche B Loan”).  The Tranche B Loan will be secured by the Company’s phage display Licensing and Funded Research Program (“LFRP”) on the same terms as the initial loan for $50 million (the “Tranche A Loan”), which was executed in August 2008.  Dyax will use the net proceeds from the Tranche B Loan primarily to fund the development and commercialization plans for its lead product candidate, DX-88.

The Tranche B Loan, which matures in August 2016, bears interest at an annual rate of 21.50%, payable quarterly, resulting in a blended interest rate of 17.38% per annum for the amended loan agreement which has a combined principal balance of $59.6 million.  Dyax may prepay the loan without penalty, in whole or in part, beginning in August 2012.  Dyax retains an interest in the LFRP revenues, including participation in revenues derived from products commercialized by Dyax licensees.  The loan agreement does not apply to Dyax’s internal drug development or to any of its co-development programs.  Upon repayment of the Tranche A and the Tranche B Loan, all rights to the LFRP revenues will revert to Dyax.  In connection with the Tranche B Loan, Dyax issued to HC Royalty a warrant to purchase an additional 250,000 shares of the Company’s common stock at a 25% premium over the average closing price for the 45-days prior to the closing date.  The warrant expires in August 2016 and is exercisable beginning on the one-year anniversary of the issuance date.

“This new agreement demonstrates confidence in the growing value of our LFRP and provides us with significant added resources in pursuing our ongoing development and commercialization goals for DX-88,” commented Gustav A. Christensen, President and Chief Executive Officer.  “Our multi-faceted business model, which includes the DX-88 franchise, our internal pipeline and the LFRP, continues to draw attractive strategic partnership and investment opportunities.  We remain committed to taking advantage of these opportunities as they arise and as we move toward the commercialization of our first product.”

“We are pleased by this expanded investment opportunity with Dyax,” commented Gregory B. Brown, M.D., Co-Founder and Managing Director of HC Royalty.  “Dyax’s phage display technology is gaining greater recognition as an effective tool for generating novel biotherapeutics, particularly in the antibody field.  We believe that, as one of the last independent licensors of antibody discovery technology, Dyax stands to earn substantial returns as compounds progress through the clinic and become commercialized.”

Please refer to the Current Report on Form 8-K that will be filed by Dyax with the Securities and Exchange Commission on or about the date hereof for additional details on the terms of the amended and restated loan agreement.

The securities offered in this transaction were issued pursuant to an exemption from and have not been registered under the Securities Act of 1933, as amended, or state securities laws and cannot be offered or sold in the United States absent registration with the Securities and Exchange Commission or an applicable exemption from the registration requirements.  This press release is neither an offer to sell nor a solicitation of an offer to buy any of the securities discussed herein and shall not constitute an offer, solicitation or sale in any jurisdiction in which such offer, solicitation or sale is unlawful.

About Dyax’s Licensing and Funded Research Program (LFRP)
Dyax provides access to its phage display libraries through various types of collaborations through its LFRP.  In this way, Dyax offers its partners therapeutic discovery capabilities and also extends its reach into non-core areas such as imaging, diagnostics, research reagents and affinity purification.  The LFRP is comprised of a number of top biopharmaceutical companies, including Amgen, Biogen-Idec, ImClone, sanofi-aventis and Wyeth, among others.  To date, Dyax has LFRP agreements with more than 70 licenses and collaborations, resulting in one approved product and thirteen clinical-stage product candidates.

About Dyax
Dyax is focused on advancing novel biotherapeutics for unmet medical needs, with an emphasis on oncology and inflammatory indications.  Dyax utilizes its proprietary drug discovery technology to identify antibody, small protein and peptide compounds for clinical development.  Dyax’s lead product candidate is DX-88 (ecallantide), a recombinant small protein that is currently being evaluated for its therapeutic potential in two separate indications.  On November 20, 2008, the U.S. Food and Drug Administration (FDA) accepted for filing the Company’s Biologics License Application for approval of DX-88 for the treatment of hereditary angioedema (HAE) and designated the application for Priority Review.  DX-88 has orphan drug designation in the U.S. and E.U., as well as Fast Track designation in the U.S., for the treatment of acute attacks of HAE.  Additionally, DX-88 is being evaluated for the prevention of blood loss during on-pump cardiothoracic surgery (CTS) through its partner, Cubist Pharmaceuticals.  Dyax licensed to Cubist the intravenous formulation of DX-88 for surgical indications in North America and Europe.  DX-88 and other compounds in Dyax’s pipeline were identified using its patented phage display technology, which rapidly selects compounds that bind with high affinity and specificity to therapeutic targets.  Dyax leverages this technology broadly with over 70 revenue generating licenses and collaborations for therapeutic discovery, as well as in non-core areas such as affinity separations, diagnostic imaging, and research reagents.  Both the Tranche B Loan announced herein and the Tranche A Loan are secured by the Company’s Licensing and Funded Research Program (LFRP).  Dyax will use a portion of the revenues generated by the LFRP to make payments to the CHRP on both of these loans, each of which mature in 2016.  Dyax is headquartered in Cambridge, Massachusetts.  For online information about Dyax Corp., please visit www.dyax.com.

About HealthCare Royalty Partners
HealthCare Royalty Partners is a global healthcare private equity firm with over $500 million in capital under management.  The firm invests principally in commercial-stage biopharmaceutical and medical device companies and products, through the purchase of royalty or Synthetic Royalty(R) interests, debt and equity.  HC Royalty’s investment team has over 100 years of healthcare related experience including principal investing, structured finance, healthcare industry senior management, Wall Street research and consulting, scientific and clinical experience.  For more information, please visit www.healthcareroyalty.com.

Dyax Disclaimer
This press release contains forward-looking statements, including statements regarding Dyax’s phage display licensing and funded research program (LFRP), the LFRP’s potential to generate future revenues and the potential for Dyax’s licensees to bring products to market.  Statements that are not historical facts are based on Dyax’s current expectations, beliefs, assumptions, estimates, forecasts and projections about the industry and markets in which Dyax competes.  The statements contained in this release are not guarantees of future performance and involve certain risks, uncertainties and assumptions, which are difficult to predict.  Therefore, actual outcomes and results may differ materially from what is expressed in such forward-looking statements.  Important factors that may affect the extent of Dyax’s patent portfolio and its potential for the identification of novel compounds include the risks that:  Dyax may not be able to obtain and maintain intellectual property protection for its phage display technology; others may develop technologies superior to Dyax’s phage display technology; and other risks that are described or referred to in Dyax’s most recent Annual Report on Form 10-K and other periodic reports filed with the Securities and Exchange Commission.  Dyax cautions investors not to place undue reliance on the forward-looking statements contained in this release.  These statements speak only as of the date of this release, and Dyax undertakes no obligations to update or revise these statements, except as may be required by law.

Dyax and the Dyax logo are the registered trademarks of Dyax Corp.