Document and Entity Information	3 Months Ended
	Dec. 31, 2011	Feb. 10, 2012
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2011
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
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		6,972,765