A 67-year-old woman presented in September 1985 with productive cough, bloody sputum, and dyspnea on exertion. Productive cough and bloody sputum had developed when the patient was 55 years old. Sputum culture and radiologic findings yielded a diagnosis of nontuberculous mycobacteriosis (NTM). Antituberculous therapy with INH, RFP, and EB was initiated in November 1987 because of the development of a cavity in the right upper lobe, and led to resolution of the lesion and clinical symptoms. Despite progression of bronchiectatic changes in both lungs and a relapse of her clinical symptoms during the following 10 years, the patient retained enough pulmonary function to be able to maintain an active daily life until she died of advanced gastric cancer at the age of 79. Autopsy revealed cystic bronchiectasis accompanied by bronchial wall thickening in both lungs, with some granuloma and acid-fast-bacteria observed in lung tissue. In this report, we concluded that patients with NTM usually experience a gradual progression of symptoms and radiographic changes during their clinical course, and that their pulmonary function may be conserved well enough to maintain an active daily life.