Pulmonary aspergillosis is being recognized with increasing frequency in recent years and the-rising incidence of this infection parallels certain medical advances in antibiotics, chemotherapeutic and immunosuppressive therapy. The cavities of lungs resulting from tuberculosis, histoplasmosis or neoplasm are apt, to be infected by one of the species of the genus Aspergillus and eventually mycetomas are formed within the cavities. Authors have experienced 6 cases of pulmonary aspergillosis forming mycetoma in Dept. of Thoracic Surgery, Catholic Medical Center from Aug. 1976 to Feb. 1979. Hemoptysis or blood tinged sputum, the predominant symptom, occurred in all cases. All patients underwent pulmonary resection, 1 pneumonectomy, 3 lobectomies, 1 lobectomy with segmental resection and 1 segmental resection and survived well without death or complication. Primary aspergillosis was in 2 cases and underlying diseases were present in 4 cases: 3 pulmonary tuberculosis, 1 bronchiectasis. The common diagnostic study of intracavitary mycetoma was the posterioanterior chest roentgenogram; in cavities suspected of being diseased or in doubtful cases, tomography was most available to find fungus ball with air-meniscus shadow.[KTCS 1979;1:1-8]