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                                                                    EXHIBIT 23.1
 
               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS
 
We consent to the reference to our firm under the caption "Experts" in the
Registration Statement (Form S-3) and related Prospectus of Cerus Corporation
for the registration of 2,000,000 shares of its common stock and to the
incorporation by reference therein of our report dated January 27, 1998, except
for Note 2 as to which the date is March 6, 1998 with respect to the financial
statements of Cerus Corporation included in its Annual Report (Form 10-K) for
the year ended December 31, 1997 filed with the Securities and Exchange
Commission and to the use of our report dated January 22, 1999, except for Note
2 as to which the date is January 30, 1999, with respect to the financial
statements of Cerus Corporation included herein.
 
Walnut Creek, California
February 10, 1999
                                            /s/ ERNST & YOUNG LLP