Objective. The frequency of gastroesophageal reflux disease (GERD) has not been fully investigated in the Asian population. The aim of this study was to investigate the prevalence of GERD, endoscopy-negative GERD (NERD), and erosive GERD in Japan, and the factors influencing disease prevalence. Material and methods. A total of 2760 subjects (mean age 50.4 years, range 24- 84 years) were prospectively enrolled in this multicenter study. GERD symptoms were assessed with the Japanese version of the Carlsson-Dent self-administered questionnaire (QUEST) and upper gastrointestinal endoscopy was performed on all study participants. Results. A total of 495 (17.9% ) individuals were diagnosed with GERD by the presence of erosive esophagitis at endoscopy and/or by the presence of GERD symptoms. Erosive esophagitis was diagnosed endoscopically in 195 (7.1% ), and symptomatic GERD was diagnosed in 351 (12.7% ) based on a QUEST score of over 6. Of these 351 subjects, 300 (10.9% ) were considered to have NERD. Male gender, hiatal hernia, and mild gastric mucosal atrophy were significant positive predictive factors of erosive esophagitis by multiple regression analysis. Hiatal hernia was the only significant predictor of GERD symptoms. Traditional Japanese foods, such as sweet cakes and rice cake, frequently exacerbated GERD symptoms. Conclusions. The prevalence of GERD in the Japanese was 17.9% and the prevalence rates of NERD and erosive esophagitis were 10.9% and 8.6% , respectively. The majority of symptomatic patients did not have endoscopically proven esophagitis. Hiatal hernia is the only important predictor of the presence of GERD symptoms. The frequency of gastroesophageal reflux disease (GERD) has not been fully investigated in the Asian population. The aim of this study was to investigate the prevalence of GERD, endoscopy-negative GERD (NERD), and erosive GERD in Japan, and the Factors influencing disease prevalence. Material and methods. A total of 2760 subjects (mean age 50.4 years, range 24-84 years) were prospectively enrolled in this multicenter study. GERD symptoms were assessed with the Japanese version of the Carlsson-Dent self-administered questionnaire (QUEST) and upper gastrointestinal endoscopy was performed on all study participants. Results. A total of 495 (17.9%) individuals were diagnosed with GERD by the presence of erosive esophagitis at endoscopy and / or by the presence of GERD symptoms. Erosive esophagitis was diagnosed endoscopically in 195 (7.1%), and symptomatic GERD was considered in 351 (12.7%) based on a QUEST score of over 6. Of these 351 subjects, 300 (10.9%) were considered to have NERD. Male gender, hiatal hernia, and mild gastric mucosal atrophy were significant positive predictive factors of erosive esophagitis by multiple regression analysis. Of exacerbated GERD symptoms. Conclusions. The prevalence of GERD in the Japanese was 17.9% and the prevalence rates of NERD and erosive esophagitis were 10.9% and 8.6%, respectively. The majority of symptomatic patients did not have endoscopically proven esophagitis. Hiatal hernia is the only important predictor of the presence of GERD symptoms.