Congenital cystic adenomatoid malformation (CCAM) of the lung is a rarest form of the congenital pulmonary cystic disease. This lesion was initially introduced in the English literature by Chin & Tang in 1949. Thereafter, many other cases were reported. In Korean literature, nine cases were reported previously. Recently we have experienced a case of CCAM born with generalized edema associated with maternal hydroamnios. This premature baby was delivered at 30 weeks of gestation. At autopsy, right lower lung showed a large cystic mass which had a connection to the bronchus. This mass compressed the superior vena cava and the right atrium. Microscopically the cystic mass was characterized by coarsely trabeculated pattern with numerous cystic spaces that were lined by respiratory epithelium or tall columnar epithelium. Gland-like spaces or alveolar spaces that are lined by simple cuboidal or columnar epithelium with occasional mucus-producing cells were also noted. Bronchial mucous gland and cartilage were not found. Other lobes of lung and the remaining organs did not show any specific anomalies.