EXHIBIT 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the use in this Amendment No. 6 to Registration Statement on Form S-1 of our report dated April 8, 2004, except as to Note 12 which is as of January 26, 2005, relating to the 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

January 26, 2005