• In Western societies, 10% to 20% of the adult population have symptoms of GERD.1,2 Although the frequency of GERD is lower,3,4 the prevalence of GERD is recently is increasing in Asian countries including Korea.5 Apart from the typical symptoms such as heartburn and acid regurgitation, and the atypical or extraesophageal symptoms such as chronic cough, globus sensation in the throat and hoarseness