Congenital cystic adenomatoid malformation[CCAM] is a rare disease that cause respiratory distress in the newborn and infants, but is one of the two causes along with lobar emphysema. This malformation has the pathologic characteristics which can be differentiated from other forms of diffuse cystic disease, i.e. CCAM is marked proliferation of the terminal bronchioles and that can enlarge rapidly by air trapping in cystic areas. The CCAM has a clinical importance because of rapid worsening respiratory distress, with tachypnea, subcostal retraction and cyanosis. This is a strict surgical condition and after operation[lobar, segmental resection or pneumonectomy] the symptoms relieved obviously. We experienced 6 cases of CCAM from July, 1980 to September, 1987 at the Department of Cardiovascular and Thoracic Surgery, Severance Hospital, College of Medicine, Yonsei University. The male patients were two and female patients were four. The age distribution was from premature to 10 year old. One of them was 27 weeks gestational premature female who was borne dead. The other 5 patients were performed on thoractomy[1 case pneumonectomy and 5 cases lobectomy]. The postoperative courses were good and no complications were seen.