EXHIBIT 31.2

I, Michael R. Cox, Chief Financial Officer, certify
that:

1.       
          I have reviewed this annual report on Form 10-K of Bioanalytical Systems, Inc.;

2.       
          Based on my knowledge, this annual report does not contain any untrue statement
          of a material fact or omit to state a material fact necessary to make the
          statement made, in light of the circumstances under which such statements were
          made, not misleading with respect to the period covered by this report;

3.       
          Based on my knowledge, the financial statements, and other financial information
          included in this annual report, fairly present in all material respects the
          financial condition, results of operations and cash flows of the registrant as
          of, and for, the period presented in this report;

4.       
          The registrants other certifying officer(s) and I are responsible for
          establishing and maintaining disclosure controls and procedures (as defined in
          Exchange Act Rules 13a-15(e) and 15d-15(e)) [clause omitted pursuant to SEC
          Release Nos. 33-8238 and 34-47986] for the registrant and have:

(a)       
          Designed such disclosure controls and procedures, or caused such disclosure
          controls and procedures to be designed under our supervision, to ensure that
          material information relating to the registrant, including its consolidated
          subsidiaries, is made known to us by others within those entities, particularly
          during the period in which this report is being prepared;

(b)       
          [paragraph omitted pursuant to SEC Release Nos. 33-8238 and 34-47986];

(c)       
          Evaluated the effectiveness of the registrants disclosure controls and
          procedures and presented in this report our conclusions about the effectiveness
          of the disclosure controls and procedures, as of the end of the period covered
          by this report based on such evaluation; and

(d)       
          Disclosed in this report any change in the registrants internal control
          over financial reporting that occurred during the registrants most recent
          fiscal quarter (the registrants fourth fiscal quarter in the case of an
          annual report) that has materially affected, or is reasonably likely to
          materially affect, the registrants internal control over financial
          reporting; and

5.       
          The registrants other certifying officer(s) and I have disclosed, based on
          our most recent evaluation of internal control over financial reporting, to the
          registrants auditors and the audit committee of the registrants
          board of directors (or persons performing the equivalent functions):

(a)       
          All significant deficiencies and material weaknesses in the design or operation
          of internal control over financial reporting which are reasonably likely to
          adversely affect the registrants ability to record, process, summarize and
          report financial information; and

(b)       
          Any fraud, whether or not material, that involves management or other employees
          who have a significant role in the registrants internal control over
          financial reporting.

|January 12, 2005 | /s/  Michael R. Cox
Michael R. Cox
Vice President, Finance, Chief Financial
Officer and Treasurer
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