SUMMARYIn a double‐blind parallel‐group study, 98 patients with symptomatic duodenal ulcer received omeprazole 20 mg o.m. and 91 cimetidine 800 mg nocte for 2 or, if then not healed, 4 weeks. After 2 weeks the healing rates on an intention‐to‐treat basis were: for omeprazole 62% and for cimetidine 33% (P<0.001), and at 4 weeks 85% and 61%, respectively (P<0.001). The proportions symptom‐free at 2 weeks were 83% of the omeprazole and 63% of the cimetidine‐group (P<0.01) and at 4 weeks 84% and 72% (P= 0.01). Patients receiving omeprazole took fewer antacid tablets than those receiving cimetidine. Patient tolerance of both drugs was similar and good. In the treatment of duodenal ulcer, omeprazole 20 mg o.m. gives faster symptom relief than cimetidine 800 mg nocte, as well as healing a greater proportion of ulcers within 2