Orthotopic cardiac transplantation has become established for selected infants with severe forms of congenital heart disease. This study reviews the combined experience and intermediate term results of infants undergoing orthotopic cardiac transplantation from Children's Memorial Hospital, Chicago, and Kosair Children's Hospital, Louisville. From June 1986 through December 1989, 20 orthotopic cardiac transplantations were performed in 19 patients. Sixteen patients had variants of hypoplastic left heart syndrome. One infant had anomalous origin of the left coronary artery with severe ischemic cardiomyopathy. Two infants had aortic stenosis with endocardial fibroelastosis, and one had extracorporeal membrane oxygenation as a bridge to transplantation. Immunosuppression included cyclosporine, azathioprine (Imuran), and corticosteroids with an effort to wean the patients from steroids by 6 months to 2 years. Three early deaths resulted--from technical errors in two patients and from hyperacute rejection in one patient at 3 days. Four late deaths have occurred. Two patients died at 2 and 13 months of acute rejection. One patient died at 15 months of acute rejection after retransplantation. One patient died at 7 months of respiratory syncytial viral pneumonia. The remaining 12 patients are surviving 5 to 47 months (means 20 months) after orthotopic cardiac transplantation. Rejection surveillance in the first 6 months is by clinical signs supplemented by echocardiography, electrocardiography, and cell cycle analysis; endomyocardial biopsy is used after 6 months of age. For the cumulative series, 24 episodes of suspected rejection have been treated during 277 at-risk patient months with intravenous methylprednisolone (Solu-Medrol) (n = 18) and monoclonal antibody (OKT3) (n = 6), for an incidence of 1.04 episodes of rejection per patient per year. Serious posttransplantation infections including endocarditis, catheter sepsis, meningitis, and colonic perforation were successfully treated in four patients. Subjectively, their quality of life is excellent as shown by normal growth and developmental milestones and a low hospital readmission rate (1.4 episodes per patient per year). These encouraging intermediate term results warrant continued application of infant orthotopic cardiac transplantation for severe forms of congenital heart disease.