Thirty-eight children, aged from a few weeks to 7 years, with severe chronic pulmonary disease and without gastrointestinal symptoms, were investigated for gastroesophageal reflux (GER), using prolonged pH probe monitoring and gastroesophageal scintiscanning. All treatments were discontinued before testing. GER was found in 24 patients (63%) (group I) and it was not observed in 14 patients (group II). All patients of group I received antireflux treatment, consisting of cisapride; in 22 of 24 patients, GER was controlled, as indicated by improvement of either pH monitoring or scintiscanning, or both. Eighteen of these 22 (82%) had remission of their pulmonary disease, and only two patients of group II (14%) had spontaneous remission of the respiratory symptoms. We concluded that GER was probably the cause of the respiratory disease in 63% of our patients, since treatment of GER was followed by disappearance of the respiratory complaints in most of them. The combination of gastroesophageal scintiscanning and pH probe study improved the diagnostic accuracy.