[GERD. Introduction].

In Japan prevalence of GERD is still low as compared to Western countries. Although it is almost certain that the number of GERD patients will not increase by increasing patients who will receive eradication in Western countries, it may be the case in Japan, because most of the H. pylori-infected subjects in Japan have a considerable level of mucosal atrophy, that can be improved after eradication of H. pylori. Indeed, prevalence of H. pylori in Japanese patients with GERD is reported to be approximately 30-40%, suggesting protective role of H. pylori infection in the development of GERD. The disease entity of Non-erosive GERD (NERD) is receiving great attention recently, but effective rate of PPI for NERD is reported to be 60%, suggesting that a considerable number of non-GERD patients are included in patients diagnosed as having NERD. Thus, an effort for improving both sensitivity and specificity of the diagnosing method for NERD is required. In any event, it should be kept in mind that pathophysiology of GERD is quite different between Western and Japanese patients.