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PRESS RELEASE
September 14, 2005

Arrowhead Appoints Virginia Dadey as Vice President, Investor Relations

PASADENA, California – (BUSINESS WIRE) – Sept. 14, 2005 – Arrowhead Research Corporation (Nasdaq:ARWR) today announced the appointment of Virginia Dadey as its Vice President, Investor Relations. Ms. Dadey has fifteen years of experience in financial markets as an investment specialist and will function as Arrowhead's nanotech investor point person. Ms. Dadey will be based in New York City, where she will call on her years of experience in institutional sales to build Arrowhead's shareholder base and to improve shareholder liquidity.

"Arrowhead is very fortunate to attract a Vice President with Virginia's particular combination of skills," said R. Bruce Stewart, Arrowhead's President. "She has a successful track record in nanotech deal-making, can call on a wide network of domestic and international analysts and fund managers, plus she can speak with authority about nanotechnology as an investment."

"I can't think of anybody better qualified to present Arrowhead's unique nanotech business model to the investment community."

Dadey, who previously worked for the Maxim Group as Senior Vice President for institutional sales, praised Arrowhead's "extremely compelling" business model. "Arrowhead is an innovator in developing and executing in the nanotech field."

"I believe this business sector has a bright future. I am very excited about joining the Arrowhead team which has been able to bridge the gap between the laboratory, where full research can be done, and the public markets without having to go through the large costs associated with the traditional venture capital model," Dadey said.

Dadey worked for the Maxim Group and its predecessor company, Investec, since 2001. Prior to working for Maxim Group, she was a vice president at Gruntal & Co. from 1996 to 2001. She received her B.S. from Purdue University.

About Arrowhead Research Corporation

Arrowhead Research Corporation (www.arrowheadresearch.com) 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.

Contacts

R. Bruce Stewart, President
Telephone: 626.792.5549
Email: bruce@arrowres.com