The purpose of this study is to assess the efficacy and safety of 8 weeks of daily treatment with Ilaprazole (5, 20 and 40 mg), once daily (QD), compared to lansoprazole 30 mg in healing subjects with endoscopically proven erosive esophagitis.

This 8 week study will be conducted by approximately 160 investigators in the United States. During this study, esophagitis healing will be evaluated by endoscopy, heartburn and other symptom relief will be evaluated by questionnaire and study drug levels will be measured.

Inclusion Criteria:

• Subject must have endoscopically confirmed erosive esophagitis as defined by the Los Angeles (LA) Classification Grading System (A-D).

Exclusion Criteria:

• Evidence of uncontrolled, clinically significant systemic disease; acquired immunodeficiency syndrome (AIDs); a condition likely to require surgery; cancer within 5 years of screening; or abnormal laboratory values.
• Co-existing diseases affecting the esophagus; history of esophageal radiation therapy, cryotherapy, or physiochemical trauma.
• History of esophageal surgery or dilatation of an esophageal stricture other than Schatzki's ring; gastric or duodenal surgery except simple oversew of an ulcer.
• Active gastric or duodenal ulcers or acute upper gastrointestinal hemorrhage within 30 days prior to screening.
• Current or history of Zollinger-Ellison syndrome or other hypersecretory conditions.
• Allergy to any proton pump inhibitor drug (omeprazole, lansoprazole, pantoprazole, rabeprazole, esomeprazole), any component of Ilaprazole, or antacid.
• Unable to tolerate lactose.
• Use of the following medications prior to randomization or anticipated use during the study: proton pump inhibitors, antacids, biphosphonates, histamine (H2) receptor antagonist (examples: Zantac, Tagamet), sucralfate, misoprostol, corticosteroids, prokinetics, Non-steroidal anti-inflammatory drugs (NSAIDs), strong anticholinergics, anticoagulant/anti-platelet aggregate therapy, anticoagulants, digoxin, theophylline, phenytoin.
• History of alcoholism or drug addiction.