The article presents the results of comparing the data on the twenty-four hours intraesophageal pH-monitoring, the esophagus investigation and the expressiveness of gastroesophageal reflux disease clinical manifestations. It has been shown that both the esophagitis presence and symptomatics severity depend upon the time of acid exposure in the esophagus. The multihour intraesophageal pH-monitoring allows to objectively prove the connection of clinical symptoms and endoscopic changes with pathologic gastroesophageal reflux.