Arrowhead Senior Advisors Featured in Nature and Nature Medicine Articles

PASADENA, Calif. – July 30, 2009 – Arrowhead Research Corporation (NASDAQ: ARWR) today announced that Scientific Advisory Board members Mauro Ferrari, Ph.D., and Chad Mirkin, Ph.D., were featured in the July 2009 editions of both Nature Medicine and Nature magazines for their outstanding work in nanomedicine.

The Nature article, titled, “Big opportunities in a small world,” may be viewed at: http://www.nature.com/naturejobs/2009/090723/full/nj7254-540a.html.

An excerpt from the Nature Medicine article, titled, “Straight talk with... Mauro Ferrari,” may be viewed at: http://www.nature.com/nm/journal/v15/n7/full/nm0709-716.html. The complete article is also available for purchase.

“Drs. Mirkin and Ferrari are true pioneers in nanomedicine and we are honored to benefit from their expertise through their deep involvement with our company,” said Arrowhead President and CEO Chris Anzalone.

“Working closely with such leaders is a critical piece of our business model. The fact that they are both featured in high impact journals in a single month is a real tribute to their contributions to science.”

About Arrowhead Research Corporation

Arrowhead Research Corporation (www.arrowheadresearch.com) (NASDAQ: ARWR) is a nanotechnology company commercializing new technologies in the areas of life sciences, electronics, and energy. Arrowhead is seeking to build value for shareholders through the progress of majority owned subsidiaries. Currently, Arrowhead has four subsidiaries commercializing nanotech products and applications and minority investments in two privately held nanobiotech companies.