 Patients who are admitted with bleeding from their rectum and clinical evidence of a significant bleeding episode elevated heart rate, low blood pressure, or need for blood transfusion have immediate upper endoscopy examination of the stomach with a flexible rubber tube with a light and video camera on the end. If this shows no source of bleeding, the patients are randomized like flipping a coin to receive a colonsoscopy examination of the large intestine with a flexible rubber tube with a light and video camera on the end either as a emergency within 12 hours or as a routine procedure 36 hours after admission. 