Of 113 patients in whom endoscopy revealed a bleeding gastric or duodenal ulcer 55 were randomly allocated to receive endoscopic sclerosis (ES) (injections of adrenaline/polidocanol) plus cimetidine while 58 received cimetidine alone as controls. 3 patients treated with ES (5.5%) compared with 25 controls (43.1%) had a major recurrent haemorrhage during their hospital stay. ES also led to significant reductions in the need for emergency surgery (3 vs 20 patients), transfusion requirements (mean 0.42 [SD 1.1] vs 2.7 (3.19) U), and the length of hospital stay (11.6 [5.1] vs 16.2 [11.3] days). ES as an adjunct to conventional medical treatment is an effective and safe emergency therapy for gastrointestinal bleeding due to peptic ulcer.