Biosource International (BIOI) 10-Q 2005 Q2 Quarterly report

Exhibit 32.1

CERTIFICATION

PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Pursuant to section 906 of the Sarbanes-Oxley Act of 2002 (subsections (a) and (b) of section 1350, chapter 63 of Title 18, United States Code), each of the undersigned officers of BioSource International, Inc., a Delaware corporation (the “Company”), does hereby certify with respect to the Quarterly Report of the Company on Form 10-Q for the quarter ended June 30, 2005 as filed with the Securi ties and Exchange Commission (the “10-Q Report”) that, to the best of the undersigned’s knowledge:

(1)the 10-Q Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)the information contained in the 10-Q Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: July 29, 2005	/s/	Terrance J. Bieker
		Terrance J. Bieker
		President and Chief Executive Officer
Date: July 29, 2005	/s/	Alan I. Edrick
		Alan I. Edrick
		Executive Vice President and
		Chief Financial Officer

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