A 62-year old woman admitted to our hospital because of an abnormal shadow on chest X-ray. Chest X-ray and computed tomography (CT) scan revealed a 2 cm nodular shadow with cavity in the right upper lobe. Bronchofiberscopy was performed, and Mycobacterium avium complex was demonstrated bacteriologically. She had been followed-up for 3 years with chemotherapy, however slow but progressive enlargement of the lesion was noted on chest X-ray. Finally she reffered to our department for surgical treatment, and right upper lobectomy was performed. Ten months after operation, there is no sign of recurrence.