Between 1971 and 1984, 57 patients with cystic fibrosis (CF) and clinically suspected gastroesophageal reflux (GER) underwent a barium-meal examination and routine pulmonary function testing. Reflux was demonstrated in 18 patients; in six of these it was complicated by hiatus hernia, esophagitis, or stricture formation. Compared with 412 CF patients without known GER, the 18 patients with demonstrable reflux had significantly reduced forced expiratory volume and forced vital capacity. GER should be looked for carefully on any barium-meal study in patients with CF; these patients have an increased incidence of reflux, with its implications for lung function, and are not good candidates for surgical intervention.