Résumé : On 1 250 patients admitted to our hospital for gastrointestinal hemorrhage from 1979 to 1987, 4% (50) had severe hematochezia with a bleeding point distal to the ligament of Treitz. Fourty-four patients needed a transfusion of the least 2 red cell units and 6 patients had hypovolemia and anemia. All the patients underwent colonoscopy with a total of 68 examinations. Precise diagnosis of the bleeding lesion by colonoscopy was made in 41 (82%). Bleeding diverticula and ulcers were the most frequent lesions. Seventeen patients were examined by angiography, which was diagnostic in 6 patients. Fourteen patients were treated endoscopically by electro coagulation. One perforation occurred and two patients had persistent bleeding. Nine patients were managed surgically; two complications occurred. No rebleeding occurred in any patient. We conclude that colonoscopy is a safe method of diagnosing the source of lower intestinal hemorrhage. Moreover, half of the 50 patients ceased to bleed spontaneously with a supportive medical therapy. © 1988 Springer-Verlag.