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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 Amendment
No. 2 to the Registration Statement (Form S-3 No. 333-72185) and related
Prospectus of Cerus Corporation for the registration of shares of its common
stock and to the use of our report dated January 22, 1999, except for Note 2 as
to which the date is January 30, 1999 and Note 5, as to which the date is March
3, 1999, with respect to the financial statements of Cerus Corporation included
and incorporated by reference herein.
    
 
                                                           /s/ ERNST & YOUNG LLP
 
Walnut Creek, California
   
March 24, 1999