Duodenal diverticula are first reported by Chomel in 1710. Duodenal diverticula are relatively common in adults with a prevalence of 23% in SRCP. The most duodenal diverticulum is asymptomatic. Complications such as obstruction, cholangitis, blliary stones, ulceration, perforation and hemorrhage can occur in approximately 10%. However, relatively few cases of bleeding from a duodenal diverticulum have been reported. The cause of bleeding from a duodenal diverticulum is uncertain and various suspected etiologies were suggested, such as ectopic gastric mucosa, stasis-induced ulceration, erosion into major vessels, aortoenteric fistuias, intradiverticujar polyp, aspirin-induced erosion. We report a case of a bleeding duodenal diverticulum by a Dieulafoy-like lesion and suggest this 1esion as one of posslble causes of blee4ng in duodenal diverticulum. (Korean J Gastroiatest Endosc 2001;23:41-44)