Brunner's gland adenoma is a rare benign tumor that is usually asymptomatic and it the result of a benign proliferation of the Brunner's glands of the duodenum. In symptomatic patients, the common clinical presentation is gastrointestinal bleeding and obstructive symptoms. A 48-year-old man presented with abdominal discomfort and vomiting. The endoscopic examination revealed a large pedunculated polypoid mass arising in the bulb and it was prolapsing through the pylorus into the antrum, and this all resulted in a ball-valve obstruction. After endoclips were applied at the peduncle of the mass, this polyp was simply and successfully cut with using an IT-knife without bleeding or perforation. We report here on a case of Brunner's gland adenoma that caused a ball-valve obstruction, and the tumor was removed by a simple and easy method with using endoclips and an IT-knife. (Korean J Gastrointest Endosc 2009;39:38-41)