Fifteen patients with both nonallergic asthma and symptomatic gastroesophageal reflux were studied before and after an eight-week period of vigorous antireflux therapy, which included ranitidine hydrochloride, 150 mg twice a day. Pulmonary and esophageal symptoms were recorded on daily diary cards. Therapy was associated with prompt amelioration of reflux symptoms and with a less dramatic and more delayed improvement in pulmonary symptoms. Objectively, esophageal erosions healed completely in eight of the ten patients who had them at the beginning of the trial, and pulmonary function measurements improved significantly. Intraesophageal infusions of physiologic saline and 0.1N hydrochloric acid in patients and healthy controls did not significantly alter pulmonary function, as measured by standard spirometry. There is a subset of patients in whom bronchoconstriction is triggered by gastroesophageal reflux. Treatment of reflux in such patients may improve their asthma.