Document and Entity Information (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Dec. 28, 2012	Mar. 31, 2012
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 30, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
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		7,638,738
Entity Public Float			$ 7,402
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes