In nine patients between the ages of 3 months and 18 years with endstage heart failure, orthotopic heart transplantation was performed. Seven of these patients suffered from dilative cardiomyopathy. Additional diagnoses were tricuspid atresia in one case, and hypoplastic left-heart syndrome in another case. Seven of these children (77.7%) were catecholamine-dependent before the operation. The postoperative immunosuppressive treatment consisted of a combination therapy of cyclosporine A, azathioprine, and prednisolone, similar to the treatment in adults. Diagnosis of rejection was based on both invasive (endomyocardial biopsy) as well as noninvasive methods (intramyocardial electrogram, echocardiography, cytoimmunological monitoring). Out of nine transplanted children and adolescents, seven are presently alive and well after a mean follow-up period of 29 months. Two patients died of graft failure. One case with irreversible renal failure, secondary to chronic cyclosporine A toxicity required kidney transplantation 2 1/2 years following heart transplantation, this being the only significant late complication up to now. Our results indicate that heart transplantation allows for survival of seriously ill children and adolescents at a similar rate as that of older patient groups. Physical and social rehabilitation has been quite favorable and has been encouraging for further pursuit of this concept.