The efficacy and safety of omeprazole, in 241 patients with active recurrent duodenal ulcer from 21 Italian centres, was studied in a multicentre double-blind randomized trial comparing 20 mg omeprazole o.m. or 40 mg famotidine nocte with endoscopic examination, symptom recording, laboratory screening and gastrin assay. In a per protocol analysis, the duodenal ulcer healing rates for omeprazole and famotidine, documented by endoscopy, were 62% (68/109) and 33% (39/117) after 2 weeks of treatment (P less than 0.001), 92% (96/104) and 80% (86/108) cumulative after 4 weeks (P less than 0.05), and 99% (102/103) and 92% (96/104) after 6 weeks (P less than 0.05), respectively. The results of this trial demonstrate that 20 mg omeprazole o.m. is superior to 40 mg famotidine nocte in duodenal ulcer healing.