Congenital cystic adenomatoid malformation of the lung (CCAML) is a rare pulmonary lesion, characterized by excessive overgrowth of the terminal respiratory bronchioles. Prenatal detection and serial sonographic study of fetuses with CCAML can provide information about the natural history of these lesions and reveal most of the nature history of pathophysiologic features which are likely to affect the clinical outcome. This information is crucial to the formulation of a prognosis and a management strategy. We report on four cases of CCAML, three of which involved macrocystic lesions including two cases of type I and one case of type II. Only one microcystic lesion, a type III CCAML, was identified in these patients. All of the cases were diagnosed by ultrasound between the 21 and 24 weeks of gestation. Fetal hydropic change was noted in all four cases. All of the parents opted for termination of pregnancy before fetal viability. Post-mortem examination confirmed the diagnosis in all four cases.