Although many studies are conducted on gastroesophageal reflux disease (GERD) and its complications, the questionnaires and reflux definitions used in the studies are different. Mayo, GERD-Q, DIGEST-Q, RDQ, and various other questionnaires that were created and have been used in the studies. The GERD definition that is mostly accepted around the world is the presence of the complaints of heartburn and/or regurgitation at least once a week. However, many different definitions, such as the presence of heartburn and/or regurgitation at least twice a week or at least once a year (if once a week, "frequent"; if once a year, "rare") and the presence of heartburn and/or regurgitation without considering the frequency and severity, were all used in the studies. Therefore, it is quite difficult to obtain a single datum by collecting these studies. However, studies including all questionnaires and reflux definitions were considered while collecting this data.Another problem encountered while performing epidemiological scanning of GERD is that when the world was separated into two parts as the East and the West, some countries that were different from each other were included in the same group (such as Iran-China and Germany-Brazil). Even though continents are considered for this separation, countries that do not resemble each other from any perspective, such as Iran and China, were included in the same group. Therefore, groups must be formed according to the higher number of ethnic distributions. There are also regional epidemiological differences even in the same country. Moreover, there is no term equivalent to heartburn and regurgitation in some Eastern languages.Turkey is geographically located in the middle of the Eastern and Western countries and the epidemiology of GERD and its complications is similar to both geographical groups (Figure 1). In the Eastern countries, the prevalence of GERD is lower and regurgitation is predominant. On the other hand, in the Western countries, the prevalence of GERD is higher and heartburn is predominant. Considering the complications, erosive esophagitis, Barrett's esophagus, and associated esophageal adenocarcinoma are seen in the Western countries more commonly.In GERD epidemiological studies performed in Turkey, the Mayo questionnaire was mostly used (1, 2). The GERD-Q form was used in one study (3). The studies in which the Mayo questionnaire was used, found the prevalence of GERD as 20% (1), 19.3% (2), 12.5% (4), and 22.8% (5,6), respectively. In the study using the other question form, the prevalence of GERD was 24.7% (3). When 5 studies were evaluated cumulatively, the prevalence was calculated to be 23%. It was observed that regurgitation was predominant in all of the studies. In the cumulative evaluation, the rate of prevalence was 23% for regurgitation and 19% for heartburn.While the date of the publications on the epidemiology of GERD goes back to the 2000s in the countries to the east of Turkey, the first articles on this subject were written in 1990s in the Western cou...