Aims of this study are to investigate the proportion of esophageal motility disorder as the cause of heartburn and/or chest pain, to evaluate the relationship among the diagnostic tools for gastroeso-phageal reflux disease(GERD) such as manometry, esophagoscopy, Bernstein test and 24 hour esophageal pH monitor and to evaluate the usefullness of each test in the diagnosis of gastroeso-phageal reflux disease by estimating its sensitivity and specificity based on 24 hour esophageal pH monitor. For this study, 106 patients with heartburn and/or chest pain and 32 controls were enrolled. The results were as follows; 1) Of 106 patients with heartburn and/or chest pain, 36 patients (34#%) have GERD and 6 patients (5.6%) have Nutcracker esophagus as a cause of this symptom. 2) One hundred and six patients were divided into the two groups on the basis of LES pressure, one comprising 14 patients with LES pressure lower than 11 mmHg and the other 92 patients with the higher LES pressure; then the group of the lower LES pressure was found to have the smaller amplitude and the shorter duration of peristaltic waves, and the higher positive rates of esophagos-copic finding. Bernstein test and 24 hour esophageal pH monitor than the other group. On the basis of reflux esophagitis finding in esophagoscopy the same 106 patients were divided into two groups, one comprising 18 patients with positive esophagoscopic finding and the other 88 patients with negative esophagoscopic finding; then the group of positive esophagoscopic finding was found to have the smaller amplitude and shorter duration of peristaltic waves, the lower LES pressure and the higher positive rate of Bernstiein test and 24 hour esophageal pH monitor than the other group. 3) The sensitivity and the specificity, evaluated with reference to the 24 hour esophageal pH monitor, were 53.6% and 90% respectively for Bernstein test, and 25% and 90% respectively for the low LES pressure. From these results, we are led to the conclusions that firstly the occupying rate of the esophageal motility disorder was 39.6% as a cause of heartburn and/or chest pain, secondly there was a relationship among the diagnostic tools for GERD, and thirdly the 24 hour esophageal pH monitor is not needed only for the diagnosis of GERD when the LES pressure was below 11 mmHg or Bernstein test was positive.