To look at the safety and improvement in symptoms of a once a day dosing of esomeprazole in children 1 to 11 years old with inflammation of their esophagus or food pipe ("esophagitis") caused by gastroesophageal reflux disease (GERD) and diagnosed by endoscopy.

To verify the healing of the esophageal inflammation if the endoscopy reveals cuts in the lining of the food pipe.

To collect information that will describe the psychological, social, and economic effects on the primary caregiver of raising children ages 1 to 5 years old with GERD.

Inclusion Criteria:

• Patients' parents/guardians must provide written informed consent prior to the execution of any study-related procedures.
• Patients who are able to comprehend their involvement in a clinical study, including risks and benefits, (typically ≥6 years of age) must have assent documented by study personnel prior to any study-related procedures.
• Patients must be diagnosed with endoscopically proven GERD by the investigator during the screening period or have a previous (within 2 weeks prior to Visit 1) diagnosis of erosive esophagitis by endoscopy and are candidates for PPI therapy.

Exclusion Criteria:

• Patients who have used a proton pump inhibitor within 14 days prior to randomization, including over-the-counter omeprazole.
• Patients who have used any prescription or over-the-counter (OTC) treatment (other than proton pump inhibitors) for symptoms of GERD, such as histamine 2 receptor antagonists or prokinetics, within 72 hours prior to randomization.
• Patients with a known hypersensitivity, allergy, or intolerance to any component of esomeprazole or omeprazole.