Document and Entity Information - shares	6 Months Ended
	Mar. 31, 2021	May 07, 2021
Cover [Abstract]
Document Type	10-Q
Document Period End Date	Mar. 31, 2021
Entity Registrant Name	APPLIED DNA SCIENCES INC
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	APDN
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		7,486,120
Entity Central Index Key	0000744452
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false