Patients with endoscopically diagnosed active duodenal ulcer disease were enrolled in a randomized, double-blind, parallel and dose-ranging trial. They were randomly assigned into four groups to be treated for up to four weeks and be seen at week 1, 2 and 4: three of ilaprazole, 5, 10, and 20 mg/day, and one of omeprazole 20 mg/day as positive control. The primary endpoint was the ulcer healing rate at week 4. Healing of ulcer was determined by its resolution from active to scarring stage. Symptoms relief was evaluated as secondary end points by using a graded score. Safety and tolerability were evaluated on basis of clinical assessments.