Fifty-nine patients with ulcerative colitis localised in the rectum, sigmoid and colon entered the trial. Thirty were treated with BDP and twenty-nine with 5-Aminosalicylic (enemas and suppositories) for 8 weeks, in a doubleblind, controlled study. Clinical, endoscopic and histological assessment was carried out before and after 4 and 8 weeks of treatment. It is concluded that BDP is a new important treatment for mild and moderate activity ulcerative colitis.