Introduction and importanceAn arteriovenous malformation (AVM) in the inferior mesenteric artery is a rare vascular pathology that accounts for 6 % of the causes of gastrointestinal bleeding. AVMs are typically classified as congenital persisting embryonic vasculature that link both systems and do not develop into arteries or veins [3], but they may also develop later in life. The majority of documented cases are iatrogenic after colon surgery.Case presentationHerein we describe a 56-year-old man who presented complaining of fresh blood per rectum with passage of clots not related to defecation with no previous similar episodes, he was found to have extensive inferior mesenteric branches AVM invading the colonic splenic flexure via Computed Tomography (CT) angiography following three non-revealing upper and lower endoscopies which was later managed surgically with left hemicolectomy with primary end to end colo-colic anastomosis.Clinical discussionAlthough AVMs seldom manifest in multiple sites through the gastrointestinal tract, it is more prevalent in the stomach, small intestine, and ascending colon, and very unusual to affect the Inferior mesenteric artery and vein and to extend to the splenic flexure colonic wall.ConclusionEven if rare, inferior mesenteric AVMs should be suspected in a patient presenting with GI Bleeding with unrevealing endoscopies, where CT Angiography is to be considered.