Seventy-seven patients with a primary complaint of persistent cough, wheezing, and/or recurrent pneumonia were evaluated for the presence of occult gastroesophageal reflux disease. Fifty-four patients (70%) had increased esophageal acid exposure on 24-hour pH monitoring of the distal esophagus. In 28% of these patients the respiratory symptoms were thought to be due to aspiration because they occurred during or within 3 minutes after a reflux episode. In the other patients, the respiratory symptoms were either induced by or were unrelated to reflux episodes. The number of respiratory symptoms reported by the patients with increased esophageal acid exposure was directly related to the presence of a nonspecific esophageal motility abnormality (p less than 0.05). This suggested that a motility disorder contributes to aspiration by promoting the aboral flow of refluxed gastric juice. Seventeen patients with increased esophageal acid exposure had an antireflux operation to relieve their respiratory complaints. Patients whose respiratory symptoms induced reflux episodes were not helped by the procedure. Of the other patients, symptoms were abolished by the procedure only in those with normal esophageal motility. It is concluded that the majority of patients suffering from chronic unexplained respiratory symptoms have occult gastroesophageal reflux disease, but only a minority of them are helped by surgery. Carefully performed esophageal function studies are needed to select those patients who will benefit from a surgical antireflux procedure.