A case of vascular malformation over the entire length of the colon and small intestine in a 41-year-old male with an almost life-long history of gastrointestinal hemorrhage, is presented. The patient's history, in connection with the findings at colonoscopy and surgery, was highly suggestive of congenital arteriovenous malformations. The long-term effect of segmental surgical resection in these cases is unknown. In view of the extent of the abnormalities, no resection was performed.