Congenital absence of the pulmonary valve (CAPV) is a rare anomaly usually associated with ventricular septal defect or Fallot's tetralogy. CAPV may be rapidly fatal in infancy because of severe disturbance of pulmonary ventilation resulting from bronchial compression by massively dilated pulmonary arteries. Other cases may be relatively benign. Our group of five cases with CAPV ranged from the severe to one case in which there was documented closure of a patent ductus arteriosus and a ventricular septal defect, leaving the CAPV as an apparently isolated, well-tolerated lesion. Plain chest radiographs play a major part in the diagnosis of CAPV since they almost invariably give some indication od the aneurysmal dilatation of the pulmonary arteries. On angiography, dilated main pulmonary arteries are shown giving rise to branches of normal or even diminished caliber.