Standard manometry is currently considered the gold standard for the classification of esophageal motor disorders. We compared the new technique of ambulatory 24-hour esophageal motility monitoring to standard manometry in 108 patients thought to have a primary esophageal motor disorder, assessed the esophageal motor pattern associated with spontaneous noncardiac chest pain, and studied the effect of long esophageal myotomy on circadian esophageal motor function. Standard manometry was found to frequently overestimate and underestimate the severity of esophageal motor abnormalities as compared to 24-hour monitoring. Ambulatory manometry showed a direct correlation of abnormal esophageal motor activity with episodes of noncardiac chest pain in 13 of 26 patients who experienced the symptom during the monitoring period. The abnormal motor activity immediately preceding the pain episodes in these patients was characterized by an increased frequency of simultaneous, double and triple-peaked, high amplitude, and long duration contractions (p less than 0.01). Long esophageal myotomy markedly reduced or eliminated the ability of the esophagus to produce these abnormal contractions (p less than 0.01). These data suggest that ambulatory esophageal motility monitoring allows more precise classification of esophageal motor disorders than standard manometry and identifies abnormal esophageal motor activity associated with noncardiac chest pain that can be abated by long esophageal myotomy.