Esophageal motility was studied in 26 children with gastroesophageal reflux. In 11 patients (group A), esophagitis was severe; in the remaining 15 (group B), either mild or no microscopic changes were found. Lower esophageal sphincter pressure and amplitude, as well as velocity and duration of esophageal pressure waves, were manometrically measured. All patients underwent a 12-week intensive antacid course. Manometric tracings, blindly read, were compared with those of 16 age-matched children with emesis without proven reflux (group C). Among the variables analyzed, amplitude of the motor waves was significantly lower in patients with severe esophagitis than in group B and C patients (P less than 0.01). Nonspecific motor defects (simultaneous, broad-based, double-peaked waves) were more commonly present in group A. At the end of therapy, symptoms had either disappeared or significantly improved. Endoscopic and histologic studies showed disappearance of the severe inflammatory changes. Manometry, repeated in patients with cured severe esophagitis, showed normalization of the amplitude and significant decrease of the nonspecific motility abnormalities. We conclude that severe gastroesophageal reflux disease in children causes esophageal motor dysfunction, resulting from esophageal inflammation. The occurrence of esophageal motility disorders only in patients with severe esophagitis and its disappearance after therapy may account for the favorable course of reflux disease in infancy.