An emergency operation was performed on a 58 year-old heterosexual male patient for massive lower gastrointestinal bleeding, which was caused by cytomegalovirus (CMV) related ulceration at the terminal ileum. Pre-operative endoscopic evaluation revealed multiple esophageal and gastric ulcerations in upper gastrointestinal tract and much fresh blood in distal colon. Angiography showed vascular tufts and extravasation of contrast medium in the cecal area. Angiodysplasia of cecum with massive bleeding was initially impressed. However, CMV enteritis was identified in the resected ileum, the diagnosis of Acquired Immunodeficiency Syndrome (AIDS) was confirmed by subsequent serological tests. AIDS was unknown to treating physicians until diagnosed by pathological specimen. Massive lower gastrointestinal bleeding related to CMV ulceration in small bowel is rare, we report this unusual presentation and highlight the the suspicion of immunocompromised state of patients with unusual, multiple gastro-intestinal ulcers.