Congenital Cystic Adenomatoid Malformation [C.C.A.M. is rare, cause acute respiratory distress in the newborn infants. The histologic features are cystic areas and marked proliferation of terminal respiratory structures. On case 1, the patient was 8-month-old male, and suffered from acute respiratory distress and cyanosis. The pulmonary cystic lesion was detected in right lung at birth and has been evaluated since birth. The study for diagnosis were chest x-ray and chest CT. A right upper lobectomy was urgently performed and he was discharged with a satisfactory postoperative course. On case 2, the patient was 20-year-old female, and suffered from cough and sputum for 2 months. The study for diagnosis were chest x-ray, chest CT, and pulmonary angiography. The cystic lesion was detected in left lung and difficult to distinguish from pulmonary sequestration. A left lower lobectomy was performed and she was discharged with a satisfactory postoperative course. We report two cases of C.C.A.M. with differential clinical course.