Press Release Details

Arrowhead Research to Report Fiscal 2011 First Quarter Financial Results and Host Conference Call on Thursday, February 10, 2011PASADENA, Calif. — February 4, 2011 — Arrowhead Research Corporation (NASDAQ: ARWR), a focused nanomedicine holding company, today announced that it will report its financial results for the fiscal 2011 first quarter ended December 31, 2010, on Thursday, February 10, 2011 after the market closes. Arrowhead management will host a conference call the same day to discuss those results and recent events at 4:30 p.m. Eastern time (1:30 p.m. Pacific time).

Interested parties are invited to participate in the conference call by dialing 877-407-4134 (toll free from the US and Canada), or 201-689-8430 (for international callers). Investors may also access a live audio webcast of this conference call on the Company's website at www.arrowheadresearch.com.

A replay of the webcast will be available approximately two hours after the conclusion of the call. The webcast archive will remain available for 90 days. An audio replay will also be available approximately two hours after the conclusion of the call and will be made available until Thursday, February 13, 2011. The audio replay can be accessed by dialing 877-660-6853 (toll free from the US and Canada), or 201-612-7415 (for international callers), and entering account number 356 and passcode 366333.

About Arrowhead Research Corporation

Arrowhead Research Corporation (NASDAQ: ARWR) is a nanomedicine company developing innovative therapeutic products at the interface of biology and nanoengineering to cure disease and improve human health. Arrowhead addresses its target markets through focused subsidiaries, which include: Calando Pharmaceuticals, a leader in delivering small RNAs for gene silencing; Ablaris Therapeutics, an anti-obesity therapeutics company; and Nanotope, a regenerative medicine company. For more information please visit http://www.arrowheadresearch.com.