Ninety-six patients with endoscopically proved active duodenal ulcers were admitted to a multicentre double-blind trial with either pirenzepine (100 mg/day, 25 mg in the morning and midday and 50 mg at bed time) or placebo for 4 weeks. Ninety-two patients (46 in each group) completed the trial. After 4 weeks, complete healing had been achieved in 70% of the pirenzepine-treated patients and in 32% of the placebo-treated ones (P less than 0.01). No important side-effects and no abnormal changes in blood values or urinalysis were observed during treatment. The difference in the ulcer healing rates observed in the two parts of this multicentre trial is briefly discussed.