Functional dyspepsia is a common symptom complex with significant impact on quality of life. There is no standard treatment for functional dyspepsia but therapeutic efficacy of proton pump inhibitor (PPI) and prokinetic agent have been proved in subsets of patients. This study has two aims:

• first is to compare the therapeutic efficacy of lansoprazole (a PPI) and mosapride (a prokinetic agent) for functional dyspepsia
• second is to investigate whether different subgroups of functional dyspepsia (e.g., epigastric pain syndrome and postprandial distress syndrome) respond differently to PPI and prokinetic agent.

Eligible outpatients with presentation of dyspepsia are enrolled if they fulfilled the criteria of ROME III criteria. A trained assistant helps the eligible patients to complete the ROME III standard questionaire, brief symptom rating scale (BSRS), and Maudsley Personality Inventory (MPI). The enrolled patients are then randomized into either lansoprazole or mosapride group for 14-day treatment. Before starting medication, right after completing the medication, and 1 month after the medication, the enrolled patients complete standardized severity questionnaire (Hong-Kong Index) to evaluate severity of dyspeptic symptoms. Symptom improvement is then determined.

Inclusion Criteria:

• aged more than 20 years old
• diagnosis of functional dyspepsia by fulfilling Rome-III criteria
• outpatient

Exclusion Criteria:

• aged less than 20 years
• organic lesions including ulcers, tumors, bleeding, vasculopathy or esophagitis as demonstrated on upper endoscopy
• concurrent illness with malignancy, diabetes mellitus, liver cirrhosis, renal failure or porphyria
• diagnosis of organic disease for dyspeptic symptoms by treating physicians
• history of abdominal surgery
• concurrent user of aspirin and NSAID
• history of allergy or severe side effects to lansoprazole or mosapride
• pregnant or lactating women