
Exhibit 23.1 - Consent of Independent Auditors


     We consent to the incorporation by reference in the Registration  Statement
(Form S-8 No.  333-56123)  pertaining to the  Bioanalytical  Systems,  Inc. 1997
Employee Incentive Stock Option Plan and in the Registration Statement (Form S-8
No.  333-56127)  pertaining  to the 1997  Bioanalytical  Systems,  Inc.  Outside
Director  Stock Option Plan of our report dated November 5, 1999 with respect to
the consolidated financial statements included in this Annual Report (Form 10-K)
of Bioanalytical Systems, Inc.

                                          /s/ Ernst & Young LLP


Indianapolis, Indiana
December 27, 1999

