Exhibit 32.1 Bio-Rad Laboratories, Inc., CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 We, Norman Schwartz and Christine A. Tsingos, of Bio-Rad Laboratories, Inc. (the "Registrant"), do hereby certify in accordance with 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to our knowledge: 1. the Quarterly Report on Form 10-Q of the Registrant, to which this certificate is attached as an exhibit (the "Report"), fully complies with the requirements of section 13(a) of the Securities Exchange Act of 1934 (15 U.S.C. 78m); and 2. the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Registrant. Dated: August 6, 2003 /s/ Norman Schwartz Norman Schwartz Chief Executive Officer Dated: August 6, 2003 /s/ Christine A. Tsingos Christine A. Tsingos Vice President, Chief Financial Officer