The purpose of this study is to assess how PPI treated GERD patients with insufficient symptom control will benefit from a change in management by providing a more efficient acid secretion inhibition during 4 weeks, by evaluation of esomeprazole 40 mg compared to pre-study PPI treatment.

Inclusion Criteria:

• Provision of informed consent
• Male or female, aged 18-65 years
• History of GERD symptoms during, at least, six months prior to enrolment
• PPI as maintenance treatment during the last 30 days prior to enrolment
• Heartburn as predominant GERD symptom, as judged by the investigator
• Persisting GERD symptoms during the past 7 days prior to visit 1, judged by the patient as either: 4 days with mild symptoms (i.e. awareness of sign or symptom, but easily tolerated)or 2 days with moderate (i.e. discomfort sufficient to cause interference with normal activities) to severe symptoms (i.e. incapacitating, with inability to perform normal activities)

Exclusion Criteria:

• Any treatment with esomeprazole during 30 days prior to enrolment History of esophageal, gastric or duodenal surgery, except for simple closure of an ulcer
• Current or historical evidence of the following diseases/conditions, as judged by the investigator:Zollinger-Ellison syndrome,Primary esophageal motility disorder, i.e. achalasia, scleroderma, primary esophageal spasm,
• Gastric or duodenal ulcers within the last three months, Malabsorbtion
• Malignancy or other concomitant disease with poor prognosis or which may interfere with the assessments in the study
• Unstable diabetes mellitus. Stable diabetes controlled by diet, oral agents or insulin is acceptable
• Patients with severe diseases or disorders which may interfere with the conduct of the study