Thirty-two cases of congenital cystic adenomatoid malformation of the lung diagnosed antenatally are reported. Antenatal diagnosis has made it possible to document the progress of the condition in utero and the postnatal prognosis. It has been possible to advise on termination and intrauterine intervention, to counsel the parents, and to plan arrangements for delivery and postnatal care among obstetricians, neonatologists, and pediatric surgeons. According to Stocker's classification there were 12 cases of type I, 15 of type II, and 5 of type III. Five pregnancies were terminated. Antenatal drainage of a cyst was performed in four patients with two survivors. Thirteen babies showed relative regression of the cyst as pregnancy progressed. After delivery the extent of the cystic malformation was assessed by chest x-rays and computed tomography scanning in 25 and angiography in 6. Treatment consisted of observation in 4, embolization in 2, operation as an emergency in 3, and electively around 4 months in 15.