The aim of this trial is to evaluate the complete remission of erosive gastroesophageal reflux disease with pantoprazole magnesium 40 mg once daily versus esomeprazole 40 mg once daily during four-week treatment with an extension treatment for non-responding patients. The study includes a baseline period up to 14 days and a treatment period of either 4 weeks (28 -2 + 5 days), or 8 weeks depending on the cure of esophagitis due to gastroesophageal reflux. The study will provide further data on safety and tolerability of pantoprazole magnesium.

Inclusion Criteria:

• Voluntary participation in the study with signature on Informed Consent Form (ICF) prior to specific protocol procedures
• Patients of any race
• On outpatient treatment
• History of frequent symptom crises related to GERD within the last 3 months (at least a frequency of twice a week, for about four to eight weeks)
• Diagnosis of erosive esophagitis (grade A to D, according to Los Angeles Classification)
• In good health condition, except GERD symptoms
• Able to follow the protocol directions and to complete daily the questionnaire ReQuest™ throughout the study

Exclusion Criteria:

• Gastrointestinal disorder, even when related to chlorhydropeptic disorders: Barret's esophagus, peptic ulcer, Zollinger-Ellison syndrome and pyloric stenosis
• Previous history of surgery to reduce acid secretion, or other upper gastrointestinal tract surgeries (excepting polypectomy and cholecystectomy)
• At initial endoscopy presenting complicated disorders due to erosive esophagitis: obstructive esophageal stenoses, Schatzki ring, esophageal diverticulum, esophageal varices, achalasia and hiatal hernia
• Pregnant women or during nursing period
• Proton Pump Inhibitors (PPIs) within the last 10 days prior to start of the study
• Triple therapy based on PPIs to eradicate H. pylori within the last 28 days prior to start of the study
• H2-blockers, sucralfate and prokinetics within the last 7 days prior to start of the study
• Systemic glucocorticoids and/or nonsteroidal anti-inflammatory drugs (including COX-2 inhibitors) for more than 3 consecutive days a week, within the last 28 days prior to start of study, with exception of regular intake of acetyl salicylic acid in dosages of up to 163 mg/day.