Document and Entity Information - shares	6 Months Ended
	Jan. 31, 2021	Mar. 15, 2021
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's Reporting Status Current	Yes
Entity Incorporation, State or Country Code	DE
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity File Number	000-25169
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jan. 31, 2021
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2021
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		114,940,165