Fifty-eight adult outpatients with endoscopically verified gastric, prepyloric or duodenal ulcers completed a double-blind trial of treatment with either cimetidine, 1 g daily, plus propantheline, 45 mg daily (group A) or cimetidine, 1 g daily, plus placebo (group B). After neither three nor six weeks of treatment was there any significant difference between the two groups with regard to ulcer healing or symptomatic relief. The ulcers of 22 (79%) of the 28 patients in group A and 25 (83%) of the 30 patients in group B were healed after six weeks, and 93% of the patients in both groups became painfree. We were thus not able to show any advantage in combining cimetidine treatment for ulcer healing with low-dose propantheline. In a small open trial the patients with healed ulcers received prophylactic treatment for 12 months with 1) cimetidine 800 mg daily, 2) cimetidine 400 mg at bedtime plus propantheline 45 mg daily or 3) propantheline 90 mg daily. No significant differences were found between the ulcer recurrence rates, but it cannot be excluded that a larger number of patients in each group might have yielded real differences.