Dieulafoy's lesion is a submucosal artery associated with a minute mucosal defect, and it is an extremely rare cause of profuse but intermittent gastrointestinal bleeding. Most cases have occurred in the proximal stomach within 6 cm of the gastroesophageal junction. Less commonly, cases are encountered in the antrum, duodenum, jejunum, colon, and rarely the rectum. Only three cases of rectal Dieulafoy's lesion have been reported in the English medical literature: one in a child and two in otherwise healthy young men. We report a case of a rectal Dieulafoy's lesion in an elderly man with a mucous fistula. Successful treatment was administered with a combination of injection therapy and heater-probe coagulation followed by elective surgical oversewing. Rectal Dieulafoy's lesions should be included in the differential diagnosis of unexplained rectal bleeding in the elderly.