Currently, congenital cystic adenomatoid malformation of the lung (CCAM) is often diagnosed antenatally by ultrasound, allowing prompt and appropriate medical and surgical management after birth. The authors report 21 cases of CCAM admitted from 1988 to 1997 to a neonatal intensive care unit and treated by high-frequency oscillation (HFO) and early surgery. Six infants developed respiratory distress, of whom 4 required ventilation by HFO. HFO was also the mode of ventilation used in all cases except 1 during the perioperative period. There was no death from respiratory failure. The authors emphasize the usefulness of antenatal diagnosis, the efficiency of HFO in cases with severe respiratory failure, and well-tolerated early surgery.