SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                  SCHEDULE 13G
                                 (Rule 13d-102)


             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
           TO RULES 13d-1(b)(c), AND (d) AND AMENDMENTS THERETO FILED
                            PURSUANT TO RULE 13d-2(b)

                                (Amendment No. 3)


                                Cerus Corporation
--------------------------------------------------------------------------------
                                (Name of Issuer)


                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                    157085101
--------------------------------------------------------------------------------
                                 (CUSIP Number)


                                  May 19, 2004
--------------------------------------------------------------------------------
            (Date of Event Which Requires Filing of this Statement)


     Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:

          [_] Rule 13d-1(b)

          [X] Rule 13d-1(c)

          [_] Rule 13d-1(d)


----------
(1)  The remainder of this cover page shall be filled out for a reporting
     person's initial filing on this form with respect to the subject class of
     securities, and for any subsequent amendment containing information which
     would alter the disclosures provided in a prior cover page.

     The information required in the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).


CUSIP No.   157085101
            ---------------------

1.      NAME OF REPORTING PERSONS
        I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

        Deerfield Capital, L.P.

2.      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [_]
                                                                      (b) [X]

3.      SEC USE ONLY



4.      CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.      SOLE VOTING POWER



6.      SHARED VOTING POWER

        509,995

7.      SOLE DISPOSITIVE POWER



8.      SHARED DISPOSITIVE POWER

        509,995

9.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        509,995

10.     CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                                                                          [_]

11.     PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

        2.31%

12.     TYPE OF REPORTING PERSON*

        PN


CUSIP No.   157085101
            ---------------------

1.   NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

     Deerfield Partners, L.P.

2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [_]
                                                                      (b) [X]

3.   SEC USE ONLY



4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.   SOLE VOTING POWER



6.   SHARED VOTING POWER

     509,995

7.   SOLE DISPOSITIVE POWER



8.   SHARED DISPOSITIVE POWER

     509,995

9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     509,995

10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                                                                          [_]

11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     2.31%

12.  TYPE OF REPORTING PERSON*

     PN



CUSIP No.   157085101
            ---------------------


1.   NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

     Deerfield Management Company, L.P.

2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [_]
                                                                      (b) [X]

3.   SEC USE ONLY



4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     New York

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.   SOLE VOTING POWER



6.   SHARED VOTING POWER

     490,005

7.   SOLE DISPOSITIVE POWER



8.   SHARED DISPOSITIVE POWER

     490,005

9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     490,005

10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                                                                          [_]

11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     2.22%

12.  TYPE OF REPORTING PERSON*

     PN



CUSIP No.   157085101
            ---------------------

1.   NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

     Deerfield International Limited

2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [_]
                                                                      (b) [X]

3.   SEC USE ONLY



4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     British Virgin Islands

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.   SOLE VOTING POWER



6.   SHARED VOTING POWER

     490,005

7.   SOLE DISPOSITIVE POWER



8.   SHARED DISPOSITIVE POWER

     490,005

9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     490,005

10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                                                                          [_]

11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     2.22%

12.  TYPE OF REPORTING PERSON*

     CO



CUSIP No.   157085101
            ---------------------


1.   NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

     Arnold H. Snider

2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [_]
                                                                      (b) [X]

3.   SEC USE ONLY



4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     United States

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.   SOLE VOTING POWER



6.   SHARED VOTING POWER

     1,000,000

7.   SOLE DISPOSITIVE POWER



8.   SHARED DISPOSITIVE POWER

     1,000,000

9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     1,000,000

10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                                                                          [_]

11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     4.52%

12.  TYPE OF REPORTING PERSON*

     IN



CUSIP No.   157085101
            ---------------------

Item 1(a). Name of Issuer:

            Cerus Corporation
            --------------------------------------------------------------------

Item 1(b). Address of Issuer's Principal Executive Offices:

            2411 Stanwell Drive
            Concord, California 94520
            --------------------------------------------------------------------

Item 2(a). Name of Person Filing:

            Arnold H. Snider, Deerfield Capital, L.P., Deerfield Partners, L.P.,
            Deerfield Management Company, L.P., Deerfield International Limited
            --------------------------------------------------------------------

Item 2(b). Address of Principal Business Office, or if None, Residence:

            Arnold H. Snider, Deerfield Capital, L.P., Deerfield Partners, L.P.,
            Deerfield Management Company, L.P., 780 Third Avenue, 37th Floor,
            New York, NY 10017

            Deerfield International Limited, c/o Hemisphere Management (B.V.I.)
            Limited, Bison Court, Columbus Centre, P.O. Box 3460, Road Town,
            Tortola, British Virgin Islands
            --------------------------------------------------------------------

Item 2(c). Citizenship:

            Mr. Snider - United States citizen

            Deerfield Capital, L.P. and Deerfield Partners,
            L.P. - Delaware limited partnerships

            Deerfield Management Company, L.P. - New York limited
            partnership

            Deerfield International Limited - British Virgin
            Islands corporation
            --------------------------------------------------------------------

Item 2(d). Title of Class of Securities:

            Common Stock
            --------------------------------------------------------------------

Item 2(e). CUSIP Number:

            157085101
            --------------------------------------------------------------------

Item 3.  If This Statement is Filed Pursuant to Rule 13d-1(b), or 13d-2(b)
         or (c), Check Whether the Person Filing is a:

    (a)[_] Broker or dealer registered under Section 15 of the Exchange Act.

    (b)[_] Bank as defined in Section 3(a)(6) of the Exchange Act.

    (c)[_] Insurance company as defined in Section 3(a)(19) of the
           Exchange Act.

    (d)[_] Investment company registered under Section 8 of the
           Investment Company Act.

    (e)[_] An investment adviser in accordance with Rule
           13d-1(b)(1)(ii)(E);

    (f)[_] An employee benefit plan or endowment fund in accordance with
           Rule 13d-1(b)(1)(ii)(F);

    (g) [_] A parent holding company or control person in accordance with
           Rule 13d-1(b)(1)(ii)(G);

    (h)[_] A savings association as defined in Section 3(b) of the
           Federal Deposit Insurance Act;

    (i)[_] A church plan that is excluded from the definition of an
           investment company under Section 3(c)(14) of the Investment
           Company Act;

    (j)[_] Group, in accordance with Rule 13d-1(b)(1)(ii)(J).

Item 4.    Ownership.

     Provide the following information regarding the aggregate number and
percentage of the class of securities of the issuer identified in Item 1.

     (a) Amount beneficially owned:

         Deerfield Capital, L.P. and Deerfield Partners, L.P. - 509,995 shares;
         Deerfield Management Company, L.P. and Deerfield International Limited
         - 490,005 shares; Arnold H. Snider - 1,000,000 shares.
          ----------------------------------------------------------------------

     (b) Percent of class:

         Deerfield Capital, L.P. and Deerfield Partners, L.P. - 2.31%;
         Deerfield Management Company, L.P. and Deerfield International Limited
         - 2.22%; Arnold H. Snider - 4.52%
          ----------------------------------------------------------------------

     (c) Number of shares as to which such person has:

         (i)   Sole power to vote or to direct the vote          0
                                                        -----------------------,

         (ii)  Shared power to vote or to direct the vote    Deerfield Capital,
                                                             L.P. and Deerfield
                                                             Partners, L.P. -
                                                             509,995; Deerfield
                                                             Management Company,
                                                             L.P. and Deerfield
                                                             International
                                                             Limited - 490,005;
                                                             Arnold H. Snider -
                                                             1,000,000.
                                                          ---------------------,

         (iii) Sole power to dispose or to direct the             0
               disposition of                             ---------------------,

         (iv)  Shared power to dispose or to direct the
               disposition of                                Deerfield Capital,
                                                             L.P. and Deerfield
                                                             Partners, L.P. -
                                                             509,995; Deerfield
                                                             Management Company,
                                                             L.P. and Deerfield
                                                             International
                                                             Limited  - 490,005;
                                                             Arnold H. Snider -
                                                             1,000,000.
..                                                         ---------------------.

     The Reporting Persons specifically disclaim beneficial ownership in the
securities reported herein except to the extent of their pecuniary interest
therein.

Item 5.    Ownership of Five Percent or Less of a Class.

     If this statement is being filed to report the fact that as of the date
hereof the reporting person has ceased to be the beneficial owner of more than
five percent of the class of securities check the following [X].


         -----------------------------------------------------------------------

Item 6. Ownership of More Than Five Percent on Behalf of Another Person.

     If any other person is known to have the right to receive or the power to
direct the receipt of dividends from, or the proceeds from the sale of, such
securities, a statement to that effect should be included in response to this
item and, if such interest relates to more than five percent of the class, such
person should be identified. A listing of the shareholders of an investment
company registered under the Investment Company Act of 1940 or the beneficiaries
of employee benefit plan, pension fund or endowment fund is not required.

         N/A
         -----------------------------------------------------------------------


Item 7.  Identification and Classification of the Subsidiary Which Acquired
         the Security Being Reported on by the Parent Holding Company or
         Control Person.

     If a parent holding company or Control person has filed this schedule,
pursuant to Rule 13d-1(b)(1)(ii)(G), so indicate under Item 3(g) and attach an
exhibit stating the identity and the Item 3 classification of the relevant
subsidiary. If a parent holding company or control person has filed this
schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating
the identification of the relevant subsidiary.

         N/A
         -----------------------------------------------------------------------


Item 8.  Identification  and  Classification  of Members of the Group.

     If a group has filed this schedule pursuant to ss.240.13d-1(b)(1)(ii)(J),
so indicate under Item 3(j) and attach an exhibit stating the identity and Item
3 classification of each member of the group. If a group has filed this schedule
pursuant to ss.240.13d-1(c) or ss.240.13d-1(d), attach an exhibit stating the
identity of each member of the group.

         N/A
         -----------------------------------------------------------------------


Item 9.  Notice of Dissolution of Group.

     Notice of dissolution of a group may be furnished as an exhibit stating the
date of the dissolution and that all further filings with respect to
transactions in the security reported on will be filed, if required, by members
of the group, in their individual capacity. See Item 5.

           N/A
          ----------------------------------------------------------------------

Item 10.   Certifications.

           "By signing below I certify that, to the best of my knowledge and
           belief, the securities referred to above were not acquired and are
           not held for the purpose of or with the effect of changing or
           influencing the control of the issuer of the securities and were not
           acquired and are not held in connection with or as a participant in
           any transaction having such purpose or effect."


                                    SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

DEERFIELD CAPITAL, L.P.

By:  Snider Capital Corporation,
     General Partner

By:  /s/ Arnold H. Snider
         ---------------------------
         Arnold H. Snider, President

DEERFIELD PARTNERS, L.P.

By:  Deerfield Capital, L.P.

By:  Snider Capital Corporation,
     General Partner

By:  /s/ Arnold H. Snider
         ---------------------------
         Arnold H. Snider, President

DEERFIELD MANAGEMENT COMPANY, L.P.

By:  Snider Management Corporation,
     General Partner

By:  /s/ Arnold H. Snider
         ---------------------------
         Arnold H. Snider, President

DEERFIELD INTERNATIONAL LIMITED

By:  Deerfield Management Company, L.P.

By:  Snider Management Corporation,
     General Partner

By:  /s/ Arnold H. Snider
         ---------------------------
         Arnold H. Snider, President

ARNOLD H. SNIDER

     /s/ Arnold H. Snider
         -------------------------


Date:  May 28, 2004



                                    Exhibit A

                                    Agreement

          The undersigned agree that this Schedule 13G dated May 19, 2004
relating to the Common Stock of Cerus Corporation shall be filed on behalf of
the undersigned.



DEERFIELD CAPITAL, L.P.

By:  Snider Capital Corporation,
     General Partner

By:  /s/ Arnold H. Snider
         ---------------------------
         Arnold H. Snider, President

DEERFIELD PARTNERS, L.P.

By:  Deerfield Capital, L.P.

By:  Snider Capital Corporation,
     General Partner

By:  /s/ Arnold H. Snider
         ---------------------------
         Arnold H. Snider, President

DEERFIELD MANAGEMENT COMPANY, L.P.

By:  Snider Management Corporation,
     General Partner

By:  /s/ Arnold H. Snider
     ---------------------------
     Arnold H. Snider, President

DEERFIELD INTERNATIONAL LIMITED

By:  Deerfield Management Company, L.P.

By:  Snider Management Corporation,

     General Partner

By:  /s/ Arnold H. Snider
     ---------------------------
     Arnold H. Snider, President

ARNOLD H. SNIDER

     /s/ Arnold H. Snider
     ---------------------------

00871.0001 #489437