Arrowhead Names Paul McDonnel as Vice President, Finance and Accounting.

PASADENA, Calif. -- Arrowhead Research Corporation (NASDAQ:ARWR), a nanotechnology company commercializing new technology in the areas of life sciences, electronics and energy, today announced that Paul McDonnel has been promoted to Vice President, Finance and Accounting. McDonnel, who was previously Corporate Controller, will take on additional responsibilities for financial reporting, Sarbanes-Oxley compliance and SEC reporting in his new position.

"Paul has proven himself to be an outstanding asset to the Arrowhead team," said R. Bruce Stewart, Arrowhead's Chairman. "His operational experience has been invaluable to completing our SOX implementation, and his experience with acquisitions and due diligence will serve us well in the future."

McDonnel has served in a variety of executive-level finance, accounting and operational positions. During his 24-year career, he has served as the CFO of Quality Imaging Products, Instashred Security Services, Reid Plastics, Inc., and Trojan Enterprises. He has also worked closely with several private equity groups in connection with merger and acquisition transactions. McDonnel is a CPA and began his career in the Los Angeles office of Arthur Andersen & Co.

McDonnel received his masters degree in management accounting and his bachelors degree in accounting from Brigham Young University.

About Arrowhead Research Corporation

Arrowhead Research Corporation is a publicly-traded nanotechnology company commercializing new technologies in the areas of life sciences, electronics, and energy. Arrowhead is building value for shareholders through the progress of majority owned subsidiaries founded on nanotechnologies originally developed at universities. The company works closely with universities to source early stage deals and to generate rights to intellectual property covering promising new nanotechnologies. Currently, Arrowhead has four subsidiaries commercializing nanotech products and applications, including anti-cancer drugs, RNAi therapeutics, carbon-based electronics and compound semiconductor materials.

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995:

This news release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. These statements are based upon our current expectations and speak only as of the date hereof. Our actual results may differ materially and adversely from those expressed in any forward-looking statements as a result of various factors and uncertainties, including the recent economic slowdown affecting technology companies, the future success of our scientific studies, our ability to successfully develop products, rapid technological change in our markets, changes in demand for our future products, legislative, regulatory and competitive developments and general economic conditions. Our Annual Report on Form 10-K and 10-K/A, recent and forthcoming Quarterly Reports on Form 10-Q and 10-Q/A, recent Current Reports on Forms 8-K and 8-K/A, our Registration Statement on Form S-3, and other SEC filings discuss some of the important risk factors that may affect our business, results of operations and financial condition. We undertake no obligation to revise or update publicly any forward-looking statements for any reason.