The influence of surgery upon the natural history of congenital heart disease is great. Children with many types of congenital heart lesions are now living to adult life. Most of these children will, however, require continuing medical care, care which traditionally has been given by the pediatrician. We have developed a method by which incidence figures and a knowledge of the natural history may be used to obtain prevalence estimates of congenital heart disease. We estimate that in the United States in 1995 there will be nearly 300,000 children under 21 years old with congenital heart disease; 38 per cent of these will have had one or more surgical procedures. In the last two decades the majority of care for children with congenital heart disease was aimed at the correction of the original lesion; however, we predict that in the next two decades an increasing fraction of medical resources will be directed toward the residua and sequelae of cardiac surgical procedures. This alteration in character of congenital heart disease will affect the patient mix seen by the cardiologist with adult patients as well as that of the pediatrician. For ventricular septal defect, pulmonary stenosis, atrial septal defect, persistent ductus arteriosus, coarctation of the aorta and tetralogy of Fallot, we have estimated the nationwide prevalence and the surgical requirements for 1995. Used with more specific local data on population and birth rate, this model can provide important input into planning the delivery of cardiovascular services.