Exhibit 32.1

CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

        I, Peter T. Kissinger, the President and Chief Executive Officer of Bioanalytical Systems, Inc. certify that (i) the Quarterly Report on Form 10-Q for the quarter ended December 31, 2003, (the "Report") fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, and (ii) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of BASi as of the dates and for the periods set forth therein.

/s/  Peter T. Kissinger Peter T. Kissinger
President and Chief Executive Officer
Date:  February 16, 2004

CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

        I, Michael P. Silvon, Vice President, Planning and Business Development and Interim Chief Financial Officer of Bioanalytical Systems, Inc. certify that (i) the Quarterly Report on Form 10-Q for the quarter ended December 31, 2003, (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, and (ii) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of BASi as of the dates and for the periods set forth therein.

/s/  Michael P. Silvon Michael P. Silvon
Vice President, Planning and Business Development
and Interim Chief Financial Officer
Date:  February 16, 2004