SUMMARY Eighty-six patients with duodenal ulcer were treated in a multicentre controlled trial with carbenoxolone capsules (Duogastrone, 50 mg four times a day for six weeks)jor a placebo. Sixtynine patients accepted endoscopy at the beginning and end of the treatment. Symptomatic responses and endoscopic improvement were significantly greater in those receiving the active preparation than in those receiving the control capsules, complete, endoscopically assessed, healing being achieved in 65 % and 20 %, respectively, of individuals having accepted endoscopy, after six weeks' treatment.