To determine how frequently bronchoscopic examination and pulmonary function testing are useful in establishing a diagnosis in patients with chronic cough as an isolated clinical symptom, we reviewed the records of all patients referred to pulmonary specialists at 3 community hospitals for evaluation of cough over a 6-yr period. There were 109 patients with the isolated symptom of chronic cough and a normal or stable chest roentgenogram. Bronchoscopy was performed in 51. All patients but 1 were followed until the cough disappeared or for a minimum of 1 yr. Carcinoma was established as the cause for cough in 1 patient. Spirometry and/or bronchial inhalation challenge was performed in 87 patients. Previously undiagnosed asthma was discovered in 39 patients by these means. Pulmonary function testing has diagnostic value in this population, but bronchoscopy is of limited value in determining the cause of isolated chronic cough.