Thirty-two patients with double outlet right ventricle (DORV) were studied between 1960 and 1976. Associated congenital defects frequently compounded the difficulty of clinical diagnosis. Cardiac catheterisation was performed in 27 patients, and the ventriculograms were studied with particular regard to the relative positions of the great vessels to each other and to the ventricular septal defect. These relationships determine which corrective operation is possible. Correction has been performed in 12 patients with a perioperative mortality of 25%. Although mitral-aortic discontinuity was demonstrated in all cases, consideration of the anatomical spectrum included in the term DORV suggests that discontinuity is not an essential feature. In common with other clinical data and in contrast with necropsy studies, none of our patients was found to show the normal relationship of the great vessels to each other, in which the aorta lies posterior and to the right of the pulmonary artery. The reason for this difference between the clinical and necropsy findings is not apparent. A similar disparity was shown with regard to pulmonary stenosis, which was demonstrated at catheterisation in 68% of the 27 patients (mean gradient 68 +/- 3 mmHg), in contrast with incidences of 18% and 25% in recent necropsy series. Patients in the necropsy studies were frequently neonates or infants, in whom death may have been the result of intractable cardiac failure secondary to excessive pulmonary blood flow. In older patients without pulmonary stenosis and with pulmonary hypertension, frequent observation is imperative so that surgical treatment can be instituted before the development of irreversible pulmonary vascular disease.