Rabeprazole, a new proton pump inhibitor, wasstudied in patients with acid-pepticrelated diseases(duodenal ulcer, gastric ulcer, GERD) in threeplacebo-controlled, double-blind, randomized clinicaltrials. Men and women over the age of 18 were enrolledif the presence of an active duodenal or gastric ulceror erosive or ulcerative esophagitis was confirmed onupper gastrointestinal endoscopy. Patients were randomly allocated to either placebo orrabeprazole 20 mg or 40 mg in the duodenal and gastriculcer protocols or to placebo or rabeprazole 10 mg, 20mg, or 40 mg in the GERD protocol. All doses ofrabeprazole in all three studies were statisticallysignificantly superior to placebo in healingacid-related lesions. There were no treatmentdifferences between the rabeprazole doses in healingactive peptic lesions. The incidence of positive [13C]ureabreath test for H. pylori was 53% in patients withduodenal or gastric ulcers. H. pylori status was noteffected by treatment with rabeprazole.