Necrotizing colitis associated with carcinoma of the colon, Known also as obstructive colitis, is a disorder characterized by anulceration and inflammation of the colon proximal to an obstructive lesion, especially carcinoma of the rectosigmoid colon, and in rare instances, leads to actual gangrene of the colon. The authors analysed radiologic findings in four cases of necrotizing colitis associated with carcinoma of the colon. Barium enema disclosed mucosal edema, nodular filling defects, irregularity of the colonic controur and typical thumbprinting appearance of involved colon proximal to an obstructing carcinoma of the colon. The mechanism of necrotizing colitis was briefly reviewed.