&NA;4‐Aminosalicyclic acid was applied topically in a daily dose of 1.4 gm for two weeks in ten patients with ulcerative colitis. After favorable results, the therapeutic effects of 4‐aminosalicylic acid and salazopyrin enemas were compared in a two‐week cross‐over open trial, in 20 patients suffering from recurrent ulcerative colitis involving the rectum and rectosigmoid. No significant difference was found in the changes of the endoscopic picture of the mucosa. The results did not show a significant difference between 4‐aminosalicylic acid and salazopyrin enemas, either in the clinical activity or in the histologic picture. 4‐Aminosalicylic acid seems to be a suitable drug for improving the clinical symptoms of ulcerative proctitis.