Document and Entity Information - shares	3 Months Ended
	Oct. 31, 2018	Dec. 21, 2018
Document And Entity Information
Entity Registrant Name	GENEREX BIOTECHNOLOGY CORP
Entity Central Index Key	0001059784
Current Fiscal Year End Date	--07-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Trading Symbol	GNBT
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Oct. 31, 2018
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2019
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		60,290,575