A high prevalence of gastroesophageal reflux disease (GER) in asthma patients has been shown in several reports from North America and Europe. However, no data from Southern Europe are available. This paper evaluates the prevalence of abnormal reflux in asthmatics, the pattern of acid reflux when present, and the relationship between asthma and GER. Eighty-one consecutive ambulatory patients with clinically stable asthma (41 women; median age 40 years, range 17-69 years) were prospectively evaluated. All patients had a thorough digestive history; baseline pulmonary function studies, including bronchoprovocation methacholine test; and ambulatory 24-hr esophageal pH monitoring. Reflux symptoms were present in 40 patients (49%). Twelve patients had abnormal GER as defined by pH testing, giving a prevalence rate of 15% (95% confidence interval 8%-24%). The presence of acid reflux was not associated with a more severe respiratory disease. Abnormal GER seems not to be a clinically significant problem in many patients with asthma in our area.