The objective of this trial was to compare the efficacy of esomeprazole, 20 mg, with that of omeprazole, 20 mg, in patients with erosive esophagitis (EE). In this multicenter, double-blind, parallel-group trial, 1176 patients with EE confirmed by endoscopy (Helicobacter pylori-negative by serology) were randomized to once-daily treatment with 20 mg esomeprazole or 20 mg omeprazole for 8 weeks. The primary outcome was the proportion of patients with healed EE through week 8. Secondary outcomes included diary and investigator assessments of heartburn symptoms. Cumulative life-table healing rates at week 8 were similarly high for 20 mg esomeprazole (90.6%; 95% confidence interval, 88.1%–93%) and 20 mg omeprazole (88.3%; 95% confidence interval, 85.5%–91.0%). The two treatments were comparable for other secondary measures and had similar tolerability profiles.