Ileocecal region is most commonly affected in intestinal Behçet's disease. Localized deep ulcerations which have a punched-out or undermining appearance with well-defined margin placing in this region had been noted in many cases. 41 patients with intestinal Behçet's disease were observed by colonofiberscope in Teikyo University Hospital from January 1982 to June 1988. In 10% (4 cases) of these patients, diffuse ulcerative lesions in the transverse colon and the distal colon were found. These diffuse lesions in the colon with Behçet's disease were seemed to be much like those associated with inflammatory bowel disease as ulcerative colitis and Crohn's disease in morphological characteristics. The clinical symptoms of these four cases with Behçet's disease including oral aphtha, genital ulcer, joint pain, skin eruptions, and eye involvement, preceded each colonic ulceration. The first two cases were affected with ulcerative lesion in the distal portion of the recto-sigmoid colon and the descending colon. And the last two were involved in the whole transversing colon by multiple deep ulcerations. Wide-spreading ulcerative lesion in the colon with Behçet's disease is a rare condition in the Japanese, and only two papers has been reported previously. Because clinical manifestations between Behçet's disease and inflammatory bowel disease are very similar in many points as oral aphthous ulcers, arthritis, eye involvement, skin eruptions, phlebitis, arterial occlusions, then, an overlapping field or a part of a spectrum of disease has been suggested by some authors. But, in the present circumstances, they are distinct disease entities, we think that these four cases are in an atypical condition with intestinal Behçet's disease.