Duodenal diverticulum is well-known pathologic entity. The incidence of duodenal diverticulum varies from 5% to 23% in the general population. Most of diverticula are asymptomatic and have been incidentally observed in upper gastrointestinal series or upper gastrointestinal endoscopy. It usually occurs in the second portion and the medial side of duodenum. The complications of duodenal diverticulum are rare but often result in significant morbidity. They include obstruction, cholelithiasis, ascending cholangitis, ulcers, hemorrhage and perforation. Major gastrointestinal hemorrhage resulting from an inflamed or ulcerated duodenal diverticulum is an uncommon event and it can be treated endoscopically. We report a case of massive upper gastrointestinal bleeding from a duodenal diverticulum which was treated endoscopically.