EXHIBIT 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the use in this Amendment No. 1 to Registration Statement on Form S-1 of our report dated March 30, 2005 relating to the consolidated financial statements of Threshold Pharmaceuticals, Inc., which appears in such Registration Statement. We also consent to the reference to us under the heading “Experts” in such Registration Statement.

/s/    PRICEWATERHOUSECOOPERS LLP

San Jose, California

October 2, 2005