There is a perception that the prevalence of gastroesophageal reflux disease (GERD) is increasing, but few studies have directly tackled this issue. By using a systematic approach, this review aimed to assess objectively whether the prevalence of GERD is changing with time. First, population-based studies that reported the prevalence of at least weekly heartburn and/or acid regurgitation were subjected to a time-trend analysis with a Poisson regression model. Second, population-based studies reporting the prevalence of GERD symptoms at 2 time points in the same source population were reviewed. Third, longitudinal studies that charted the prevalence of GERD symptoms and esophagitis in primary and secondary care were examined. The Poisson model revealed a significant (P < .0001) trend for an increase in the prevalence of reflux symptoms in the general population over time. Separately, significant increases with time were found for North America (P = .0005) and Europe (P < .0001) but not Asia (P = .49). Studies of the same source population over time indicated an increase in the prevalence of GERD in the U.S., Singapore, and China but not Sweden. An increase in the prevalence of GERD or esophagitis was found in the majority of longitudinal studies. There is evidence that the prevalence of GERD has increased during the past 2 decades. If this trend continues, it could contribute to the rapidly increasing incidence of more serious complications associated with GERD, such as esophageal adenocarcinoma, as well as costs to healthcare systems and employers.