Cytomegalovirus (CMV) infections are usually reported in immunocompromised patients. However, it occurs rarely in immunocompetent individuals. We report a case of 64-year-old male patient who was immunocompetent and developed massive lower gastrointestinal bleeding. Colonoscopic examination showed normal except for bleeding coming from terminal ileum. Angiography revealed active bleeding from distal ileum and the bleeding was controlled by coil embolization. However, three days later, hematochezia redeveloped. To control persistent bleeding, we resected a large ileal ulcer, which proved to be an isolated ulcer containing cells with CMV inclusion bodies. In the reported case of massive lower gastrointestinal bleeding related to CMV ulceration, the site of hemorrhage was usually the cecum rather than the small intestine. This case suggests that hemorrhage due to CMV infection of the ileum may occur in immunocompetent host without endoscopic evidence of colonic involvement. (Korean J Gastroenterol 2002;39:59-63)