Thirty-nine patients with bleeding vascular malformations were evaluated. The age range was from 3 to 78 years, with a bimodal age distribution. The younger patients had no associated diseases, while those in the older category invariably had an associated cardiac lesion (aortic stenosis in 12 patients and severe atherosclerotic disease in 11 patients). With experience, colonoscopy has become a valuable adjunct to arteriography with the lesion visualized in 12 patients. Arteriography is the most useful study being diagnostic in 35 of 38 cases. Exploration alone was diagnostic in only one of 39 patients. The most common site of bleeding was the cecum (21 patients) followed by the proximal small intestine (eight patients), terminal ileum (seven patients), and ascending colon (five patients). The lesions in the proximal small bowel were much more common in the younger patients and were believed to be congenital. Resection controlled the bleeding in the majority of patients, although four recurrences have been noted. All have been documented angiographically to have been from a new lesion and two were controlled with reoperation. The key elements to control of these patient's bleeding include: (1) systematic work-up with a team approach emphasizing careful visceral angiography, and (2) the avoidance of a premature laparotomy prior to complete evaluation.