We report a case of tuberculous infection of emphysematous bulla, who is a 71-years-old male and ex-smoker. He had no past-history and had been treated for chronic obstructive pulmonary disease. At the periodical consultation on Sept 28 '95, abnormal shadow was found in left middle lung field on plain chest X-ray without any exacerbation of symptoms. Nearly alllaboratory tests on admission were within normal limit, except of slight elevation of inflammatory markers and slight hypoxemia. The Mantoux's skin test was positive. Roentogenologically, the air-fluid level was detected in the bulla of superior segment of left lower lobe. By percutaneous thoracentesis of the bulla under fluoloscopy and ultrasonic echo-guide, the fluid in the bulla was obtained. The fluid was exudate, the activities of ADA and LDH were elevated, but neutrophils were more dominant than lymphocytes in the fluid. The MTD test was positive, which amplifies rRNA of Mycobacterium tuberculosis (MTB), and MTB were cultered after four weeks from the fluid. However, MTB was not cultured from sputum and bronchial washing of left S6 via bronchoscope. After the administration of RFP, INH and EB, the fluid gradually disappeared with reduction of the size of bulla. We discussed the usefulness of the examination of the fluid in the bulla, especially the measurement of the activity of ADA and the MTD test for the confirmation of diagnosis as tuberculosis.