Dr. Reginald E. Greene: The patient is a 51-year-old white man who entered the Massachusetts General Hospital because of shortness of breath on exertion. He had had this symptom for one year. He had been in his usual excellent state of health, except for chronic postnasal drip, until 14 months previously, when an upper-respiratory tract infection with cough and nasal crusting developed. The cough increased and was occasionally productive of yellow sputum; there was no hemoptysis. Roentgenograms obtained nine months before his admission showed bilateral pulmonary infiltrates, whereas three years previously the roentgenogram of the chest had been normal. He was admitted to another hospital where bronchoscopy, cytologic study, and sputum examination for acid-fast bacilli were negative. His symptoms persisted, and a few months later bronchoscopy was performed to remove secretions. This relieved the cough, which almost disappeared. A decreased exercise tolerance developed which was associated with dyspnea and fatigability.