Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the 1999 Equity Incentive Plan of Cerus Corporation of our reports dated February 22, 2006 with respect to the financial statements of Cerus Corporation, Cerus Corporation’s management’s assessment of the effectiveness of internal control over financial reporting, and the effectiveness of internal control over financial reporting of Cerus Corporation included in its Annual Report (Form 10-K) for the year ended December 31, 2005, filed with the Securities and Exchange Commission.

/s/    Ernst & Young, LLP

Palo Alto, California

August 7, 2006