UNITED STATES

                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549



                                    FORM 8-K

                                 CURRENT REPORT


     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934


                Date of Report (Date of earliest event reported)

                                 April 23, 2004


                          BIOSOURCE INTERNATIONAL, INC.
             (Exact name of registrant as specified in its charter)


              Delaware                   0-21930                 77-0340829
  (State or other jurisdiction of  (Commission File Number)    (IRS Employer
           incorporation)                                    Identification No.)



        542 Flynn Road, Camarillo, California                      93012
       (Address of principal executive offices)                  (Zip Code)

       Registrant's telephone number, including area code: (805) 987-0086






Item 7. - Financial Statements, Pro Forma Financial Information and Exhibits.

          (a) Financial Statements. None.

          (b) Pro Forma Financial Information. None.

          (c) Exhibits.

              99.1   Press Release dated April 23, 2004, published by BioSource
                     International, Inc. (the "Company").

Item 12.  Results of Operations and Financial Condition.

         On April 23, 2004, the Company issued a press release regarding its
financial results for the first quarter ended March 31, 2004. A copy of the
press release is attached hereto as Exhibit 99.1 and is incorporated herein by
this reference.

         The information in this report shall not be deemed "filed" for purposes
of Section 18 of the Securities Exchange Act of 1934, nor shall it be deemed
incorporated by reference in any filing under the Securities Act of 1933 or the
Securities Exchange Act of 1934, except as shall be expressly set forth by
specific reference in such a filing.







                                   SIGNATURES

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                                   BIOSOURCE INTERNATIONAL, INC.



April 23, 2004                                     /s/ Charles C. Best
                                                   -----------------------------
                                                   Charles C. Best
                                                   Chief Financial Officer








                                  EXHIBIT INDEX


    Exhibit Number       Description

        99.1             Press Release dated April 23, 2004, published by
                         the Company.