This prospective randomized trial compares the results of i.v. omeprazole and i.v. ranitidine in 45 patients admitted as an emergency with an endoscopic diagnosis of bleeding duodenal ulcer. The patients were randomized to receive i.v. omeprazole, 40 mg bolus followed by 80 mg/day by continuous infusion for 3 days (group A), or ranitidine 50 mg i.v. bolus followed by 400 mg/day i.v., continuous infusion for 3 days (group B). Follow-up endoscopy on day 4 demonstrated successful therapy, except when more than 4 units of blood/day had to be transfused to maintain hemoglobin level above 10 g/l. Bleeding stopped in 20/21 patients in group A (95.2%), and in 17/24 patients in group B (70.80%) (p < 0.05). From the results of the study, it can be concluded that intravenous omeprazole seems to be effective in the control of bleeding duodenal ulcer.