Document and Entity Information - shares	6 Months Ended
	Jan. 31, 2018	Mar. 16, 2018
Document And Entity Information
Entity Registrant Name	GENEREX BIOTECHNOLOGY CORP
Entity Central Index Key	0001059784
Document Type	10-Q
Document Period End Date	Jan. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--07-31
Is Entity a Well-known Seasoned Issuer?	No
Is Entity a Voluntary Filer?	No
Is Entity's Reporting Status Current?	Yes
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		1,065,093
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2018