This multi-center, double blind, randomized trial aims to compared the efficacy and safety profiles of sodium alginate oral suspension (50 mg/ml) 20 ml three times daily with that of omeprazole (20 mg/capsule) 1 capsule once daily for the treatment of non-erosive reflux disease (NERD) patients in Taiwan. Patients will be included into study if they are diagnosed as NERD; with heartburn or regurgitation (either one) as main symptom at least 2 days a week and had been present for ≧1 month before screening; with heartburn or regurgitation (either one) during the 7 days screening period, either with frequency for ≧4 days of mild symptom, or ≧ 2 days of moderate to severe symptom; and have signed the informed consent. Patients will be excluded if they are diagnosed as erosive gastroesophageal reflux disease (GERD), Barrett's esophagus or esophageal stricture; with active or healing gastroduodenal ulcer (except scars); with history of gastric, duodenal or esophageal surgery; with intrahepatic stone, gallstone, gallbladder sludge, hepatic or pancreatic carcinoma as evidenced by abdominal ultrasonography, with ischemic heart disease as evidenced by electrocardiogram; taking a proton pump inhibitor (PPI) within 14 days before screening, or a H2-blocker, prokinetic agent or antacid within 7 days before screening; or with clinically significant liver or kidney disease. The primary efficacy endpoint is percentage of patients achieving adequate heartburn (defined as a burning feeling or pain behind the breast bone) or regurgitation (defined as an acid taste in the mouth or unpleasant movement of material upwards from the stomach) relief at day 28 as assessed by patient diary. The secondary efficacy endpoints are percentage of patients achieving adequate heartburn or regurgitation relief at day 14; change from baseline of the reflux disease questionnaire total score at day 14 & 28; patients' overall satisfaction at the end of study; and number of antacid used during the 4-week treatment period. The safety endpoints are incidence of adverse events, and changes in laboratory test results (hematology, biochemistry, and urinalysis). The study hypothesis is that treatment with sodium alginate is non-inferior to omeprazole in relieving heartburn or regurgitation symptoms of the NERD patients.