Mesenteric arteriovenous fistulas are a rare entity. Those involving the inferior mesenteric artery are exceptionally rare with only 13 cases reported in the English literature,1,2 of which only one has been associated with ischemic colitis. Ischemic colitis is a well-recognized clinical entity that typically occurs spontaneously in elderly patients and is not associated with a specific clinical presentation.3 We report a case of ischemic colitis caused by venous hypertension associated with a congenital inferior mesenteric arteriovenous fistula. To our knowledge, this is the first reported case of a mesenteric arteriovenous fistula causing ischemic colitis in a patient without previous gastrointestinal surgery or trauma.