The patient, an 81-year-old woman, was admitted to our hospital for a detailed examination; the chief complaint being melena. An upper gastrointestinal roentgenologic study revealed a submucosal tumor with a smooth surface and a stalk measuring 50 mm at the third part of the duodenum. Endoscopy depicted it as a yellowish submucosal tumor. Based on computed tomography and fluoroscopy of the small intestine, a diagnosis of duodenal lipoma was made. The esophagus, stomach, and the small and large intestines were free of lesions so the duodenal lipoma was judged to be the hemorrhagic source. The tumor was endoscopically polypectomized using a 2-channel scope. The excised specimen, measuring 50 x 20 x 20 mm, was covered by a normal duodenal mucosa with small ulcers in part. Photomicrographic findings included a tumor that was composed of mature adipose tissue in the submucosa, which coincided with a diagnosis of lipoma. Small ulcers had formed in part, exposing vessels, thus indicating the cause for hemorrhage. Lipoma is a benign tumor; and if the lesion is found to be pedunculated and an endoscope can reach it for treatment, minimally invasive endoscopic procedures should be selected.