The Differentiation between the two most frequent chronic inflammatory conditions of the intestines, ulcerative colitis and regional enterocolitis (syn.: granulomatous enterocolitis, Crohn's disease) may be readily made from conventional barium x-ray examinations in patients with typical intestinal lesions. In advanced cases with widespread severe changes, however, such a distinction is often difficult (11). The prognosis regarding development of malignant tumors in the bowel differs for the two conditions. Their types of complications are dissimilar and often require a different surgical approach. Consequently, every reasonable diagnostic procedure should be employed for their differentiation. The angiographic appearance of ulcerative colitis has been described by others (2, 8, 9, 12), but mesenteric angiography in regional enterocolitis does not seem to have been reported in the literature. Because of the clinical importance of distinguishing the two diseases, angiographic studies must be regarded as ju...