Document And Entity Information - shares	3 Months Ended
	Dec. 31, 2016	Feb. 09, 2017
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q1
Entity Registrant Name	BIOANALYTICAL SYSTEMS INC
Entity Central Index Key	0000720154
Current Fiscal Year End Date	--09-30
Entity Filer Category	Smaller Reporting Company
Trading Symbol	BASI
Entity Common Stock, Shares Outstanding		8,107,677