Gastrointestinal bleeding frequently manifests as a severe, life-threatening condition. The pathological conditions of the pancreas rarely associate with rectal hemorrhage. The history of a male patient with cancer of the tail of the pancreas, which invaded the large bowel and manifested clinically as a severe lower gastrointestinal bleeding, is reported. Repeated colonoscopy diagnosed a necrotising tumor mass which was communicating with the bowel through a fistula. Neoplasms of the tail of the pancreas usually do not cause early symptoms, therefore extra pancreatic extension and invasion of other organs are relatively common at the time of diagnosis. When managing patients with distal gastrointestinal bleeding, the possibility of malignancy originating from other organs other than the large bowel must always be borne in mind.