A term newborn infant with congenital cystic adenomatoid malformation of the lung is described to enhance appropriate and early diagnosis. The patient was initially misdiagnosed and subrmited to abdominal surgery for repair of left diaphragmatic hernic on the basis of early onset respiratory distress, right displacement of cardiac apical impulse, rightward mediastinal shift and abnormal left lung areolar changes in thoracic X ray films, in spite of normal nasogastric tube position. Correct diagnosis was suspected alter evidence of diaphragmatic indemnity at laparotomy and it was finally confirmed by computed axial tomography at age thirty hours. After resection of the afected lung segment at age five days, the patient required permanent mechanical respiratory assistance with high pressure and frequency settings, and had several episodes of neumothorax, including bronchopeural fistulae, dying finally at age 18 days. Necropsy findings showed left bronchopleural fistula and signs of exudative stage of bronchopulmonary dysplasia. Congenital cystic adenomatoid malformation of the lung represents 25% of congenital pulmonary malformations. Survival of petients depends on the magnitude of pulmonary involvement, time at diagnosis and early surgical correction. Most frequent complications are persistent pulmonary hypertension, barotrauma secondary to ventilatory assistance and infection.