A 23-year-old man presented with tarry stool and severe anemia. Upper endosdopic examination revealed a pedunculated polyp protruding from the SDA of the duodenal bulb. Endoscopic ultrasonography showed a slightly hyperechoic mass connecting with the third layer of the duodenal wall and cystic structure in the tumor. Based on the examination, gastrointestinal bleeding was attributed to the polyp, and we performed endoscopic polypectomy without any complication. The resected specimen was 20mm in maximal length, and histopathological diagnosis was Brunner's gland hyperplasia. Endoscopic polypectomy is an useful treatment for the duodenal Brunner's gland hyperplasia causing gastrointestinal bleeding.
