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)

                                October 20, 2003


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

            Delaware                      0-21930                77-0340829
(State or other jurisdiction of        (Commission             (IRS Employer
         incorporation)                File Number)          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 5. - OTHER EVENTS.

On  October  20,  2003,  the  Company  issued  a press  release  announcing  the
appointment  by the  Company's  Board of  Directors of Terrance J. Bieker as the
Company's new  President and Chief  Executive  Officer,  commencing  November 3,
2003. Mr. Bieker will also be appointed to fill the vacancy created on the Board
of Directors of the Company by the resignation of Len Hendrickson. A copy of the
press release is attached hereto as Exhibit 99.1 and is  incorporated  herein by
this reference.

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  October 20,  2003,  published by
                         BioSource International, Inc. (the "Company").





                                   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.



October 20, 2003                                     /S/ CHARLES C. BEST
                                                     -----------------------
                                                     Charles C. Best
                                                     Chief Financial Officer





                                  EXHIBIT INDEX


EXHIBIT NUMBER            DESCRIPTION
- --------------            -----------

     99.1                 Press Release dated October 20, 2003, published by the
                          Company.