SUMMARY A rare case of congenital cystic adenomatoid malformation of the lung is presented. The patient had a history of recurrent lung infections of the right lower lobe, which were reported since his childhood. The x-ray as well as the computerized scanning tomography of the chest showed an abnormality of the right lower lobe with central cavitation. The patient was submitted to right thoracotomy and a lower lobectomy was performed. The postoperative course was uneventful and the patient was discharged from the hospital one week postoperatively with a normal chest x-ray. Pneumon 1999, 12 (2): 141-146