To compare esomeprazole with omeprazole for healing erosive esophagitis (EE), 1148 patients with endoscopically confirmed EE were randomized to once-daily esomeprazole, 40 mg, or omeprazole, 20 mg, for 8 weeks in this multicenter, double-blind, parallel-group trial. The primary outcome was the proportion of patients with healed EE at week 8. Secondary outcomes included diary and investigator assessments of heartburn symptoms. At week 8, estimated healing rates were 92.2% (95% CI, 89.9%–94.5%) with esomeprazole and 89.8% (95% CI, 87.2%–92.4%) with omeprazole. Healing rates with esomeprazole were significantly higher than those with omeprazole at weeks 8 (88.4% vs 77.5%; P = 0.007) and 4 (60.8% vs 47.9%; P = 0.02) in patients with moderate to severe (Los Angeles grade C or D) EE at baseline but were not significantly different for patients with mild (Los Angeles grade A or B) EE. Both treatments were comparable for other secondary measures and had similar tolerability profiles.