We evaluated the prevalence of gastroesophageal reflux in 36 children, 22 (61.2%) male and 14 (38.8%) female (median age, 75.5 months; range, 18-178), with noncontrolled asthma by means of prolonged (22-24 h) esophageal pH monitoring. None of the children had gastrointestinal symptoms suggesting gastroesophageal reflux. Atopy was seen in 21 of 36 (58.3%) patients. Pathological gastroesophageal reflux was present in 27 (75%) children. All patients were given cisapride (0.2 mg/kg q.i.d.) for 3 months. A clinical and pharmacological score was determined, and a second pH-metric study was made at the end of the follow-up period. The following pH-metric parameters were evaluated: the total percentage of time pH was < 4, the number of reflux episodes, the number of reflux episodes lasting > 5 min, the length of the longest single reflux episode, and the percentage of time the esophageal pH was < 4 during sleep. The study was completed in 11 of 27 children. The percentage of time that esophageal pH was < 4 improved in nine of 11 (81.8%) patients (p = 0.013). The percentage of time that esophageal pH was < 4 during sleep showed the most significant decrease (p = 0.002) after treatment. Improvement in both clinical and pharmacological scores was highly significant (p < 0.0001) in 19 of 27 patients, eight of whom did not want to repeat the pH study. We conclude therefore that gastroesophageal reflux is frequently associated with noncontrolled asthma and that medical therapy for reflux may improve the further course of respiratory disease.