Fifty-five patients with active duodenal ulcer have completed, up to today, a one-month double-blind trial to compare the effects of pirenzepine (150 mg daily), cimetidine (1 g daily) and placebo on the healing of duodenal ulcer. Fifteen (71%) of the 21 patients treated with pirenzepine had healed ulcers compared with 14 (82%) receiving cimetidine (P less than 0.05. In the placebo group there were 7 (41%) healed ulcers. Symptomatic improvement in patients given pirenzepine was as substantial as in cimetidine-treated patients. No adverse effects were noted.