A series of 72 patients with proved double-outlet right ventricle was studied with reference to the ability of angiocardiography to determine the location of a ventricular septal defect when it was associated with various great-artery relationships. Only 2 of the 72 patients had an intact ventricular septum. The other 70 patients had 16 possible anatomic variations based on four positions of the ventricular septal defect (subaortic, subpulmonary, subaortic and subpulmonary, and remote type) and four great-artery relationships (normal, side by side, dextromalposition, and levomalposition). Using the hemodynamic information regarding systemic and pulmonary arterial saturations, combined with biplane angiocardiographic data from the right ventricle (and if possible with left ventriculography), one can predict the location of ventricular septal defect. Because the different types of double-outlet right ventricle have different surgical approaches, this information can be important to the surgeon.