Three cases, in each of which an aorticopulmonary septal defect (AP window) coexisted with a ventricular septal defect, are described. In two the ventricular septal defect was of the usual variety, and in one it was part of the tetralogy of Fallot. The patients presented as examples of congestive cardiac failure with a large left to right shunt in infancy. Aortography was the most reliable method for identification of the AP window when a ventricular septal defect was associated. Associated features included a right aortic arch with mirror image branching in the first case and tetralogy of Fallot with muscular subaortic stenosis in the third case. In the case with the tetralogy of Fallot, the effects of pulmonary stenosis were masked by the left to right shunt through the AP window.