Esophageal manometry was performed before and after the operations for esophageal disorders in children to evaluate lower esophageal sphincter (LES) function and motility of the esophagocardiac region in each disease. Patients who underwent radical operations for gross C-type esophageal atresia (EA) and those with hiatal hernias considered to have gastroesophageal reflux (GER) showed reduction in LESP and LESL and eosphagocardiac motor abnormalities. Lower esophageal sphincter pressure and length, and motility of the esophagocardiac region improved in six patients who underwent an antireflux operation. Abnormal esophageal waves in EA patients persisted even after improvements in LES function by the antireflux operation and were considered to be a congenital problem, as the literature suggests. Effects of surgical intervention on the esophagus on the LES function were studied. Lower esophageal sphincter and esophagocardiac function were preserved, and GER did not develop after Livaditis' procedure for EA or esophageal transection and sectioning the esophageal branch of the vagus nerve for esophageal varices. Anatomic abnormalities that lead to LES dysfunction are considered to cause GER.