DeMester Score (DMS) is a composite score first reported in 1974 for the diagnosis of gastroesophageal reflux disease (GERD) in ambulatory pH-impedance monitoring. Recently, Lyon consensus supported a more objective evaluation of patients considering diagnosis only if specific endoscopic findings or when acid exposure time (AET) is greater than 6%. The aim was to compare agreement between DMS and Lyon´s criteria for the diagnosis of GERD.