Document and Entity Information	9 Months Ended
Jun. 30, 2011	Aug. 09, 2011
Document Type	10-Q
Amendment Flag	true
AmendmentDescription	We are filing this Amendment to correct the cover page, which did not have a box check marked to indicate that we had submitted electronically and posted on our corporate website every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months, and to clarify that the numerical information in Footnote 3 to the condensed consolidated financial statements included in Part 1, Item 1 of the report is not in thousands. Except as set forth in the immediately preceding sentence, this Amendment does not alter or restate any of the information set forth in the Original Filing. In addition, this Amendment No. 1 does not reflect any subsequent events occurring after August 15, 2011, the original filing date of our Form 10-Q.
Document Period End Date	Jun. 30, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Trading Symbol	BASI
Entity Registrant Name	BIOANALYTICAL SYSTEMS INC
Entity Central Index Key	0000720154
Current Fiscal Year End Date	--09-30
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		6,912,511

Description of changes contained within amended document.

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