Gastroesophageal reflux disease (GERD) is a common, potentially serious and very costly problem in Western countries, and has an increasing prevalence in Asian countries. GERD is a spectrum of diseases, which includes typical symptoms of heartburn, regurgitation and dysphagia, signs of erosive esophagitis and its complications, and a range of extraesophageal manifestations. There is no absolute gold standard for the diagnosis of GERD. Four methods alone or in combination can be used to establish the diagnosis. Medical treatment using a proton pump inhibitor is very effective in patients with typical symptoms or erosive esophagitis. However, the responses in patients with extraesophageal manifestations are usually less satisfactory. The findings from many clinical reports have suggested a significant association between tooth erosion and GERD, but more information is needed for a better understanding of this association.