EXHIBIT 23.1 The undersigned hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of the report of the undersigned dated December 23, 2003, relating to the financial statements of Arrowhead Research Corporation, which appears in the Annual Report on Form 10-KSB of Arrowhead Research Corporation for the year ended September 30, 2003. The undersigned also consents to the references to the undersigned under the heading "Experts" in such Registration Statement. /s/ Kevin Breard, CPA - --------------------- KEVIN BREARD, CPA, AN ACCOUNTANCY CORPORATION Northridge, California February 23, 2004 II-7