This is a Phase 3, randomized, double-blind, multi-center, active-controlled, 3-arm study with an 8-week treatment period. This study will compare the efficacy of dexlansoprazole MR (60 mg QD and 90 mg QD) with that of lansoprazole (30 mg) when administered orally as a single daily dose in the morning, before breakfast. The study is designed to evaluate healing of erosive esophagitis and the effect of the therapy on relieving gastroesophageal reflux disease-related symptoms. The study consists of two periods, a screening period (maximum 21 days) and a treatment period, which will last 8 weeks.