A Study to Investigate the Pharmacodynamic Effect After Four-week Omeprazole Treatment of Non-erosive Reflux Disease in a Japanese Population

Inclusion Criteria: * Patients who identified their predominant symptom as heartburn and were classifiend as Grande M or N according to Hoshihara's modofied version of Los Angeles Classification at esophagogastroduodenoscopy. Written informed consent, ability to comply with study instructions Exclusion Criteria: * Patients with any ongoing gastrointestinal bleeding at the time of esopgahogastroduodenoscopy, patients with any history of erosive esophagitis or any other major diseases or concommittant drugs likely to interfere with the evaluation of this study