20 outpatients with acute peptic ulcer were treated with ranitidine 50 mg i.v. twice daily in an open trial. 92% of the duodenal ulcers and 80% of the gastric ulcers were healed after four weeks treatment. The rapid symptomatic improvement noted during the patients daily visits was particularly impressive. The results of our study show that the commonly practised intravenous treatment of peptic ulcers is also practicable with a modern drug possessing a clearly defined mode of action.