Massive per rectal bleeding caused by a Dieulafoy's ulcer located within the rectum is extremely rare. We herein report such a case occurring in a 76-year-old male patient with a history of chronic renal failure, who presented with massive fresh bleeding in the rectum. He was diagnosed during an endoscopic inspection and was promptly treated by clipping at the same time. Although this is a rare entity, Dieulafoy's ulcer should therefore be taken into consideration in the differential diagnosis of patients presenting with massive lower gastrointestinal bleeding.