The study was carried out on two groups of patients with esophageal scleroderma (LES pressure less than 5 mm Hg and amplitude of smooth muscle pressure waves less than 10 mm Hg): one group included patients with mild (group M) and the other severe (group S) gastroesophageal reflux (GER) diagnosed by ambulatory esophageal pH monitoring. Nine normal subjects were used as controls. Antroduodenal motility was recorded by means of manometry for 200-300 min after an overnight fast and the gastric emptying (T1/2) of a semisolid meal was measured utilizing a scintigraphic method. Patients of group S showed a significantly lower incidence of migrating motor complex activity fronts, as well as a more delayed gastric emptying, compared with those of group M. The reason that patients with the same degree of esophageal motor impairment have different degrees of GER may lie in the fact that the concomitant impairment of gastrointestinal interdigestive cyclic clearing activity and the delay in gastric emptying may allow a larger quantity of material to remain stagnant in the gastric lumen, readily available for gastroesophageal reflux.