We present a case of congenital cystic adenomatoid malformation of the lung (CCAM) diagnosed at 23 weeks of gestation with concomitant fetal hydrops. The sonographical picture of CCAM disappeared in the third trimester of pregnancy and fetal hydrops resolved under medication with digitalis to the mother. The neonate showed mild dyspnea; the prenatal diagnosis of CCAM was confirmed by chest X-ray and computed tomography. The affected lung segments were dissected at 5 days of age. The diagnosis of CCAM type III was confirmed histologically.