From 1986 to February 1993, 40 children aged 2 months to 18 years (average age 10.4 +/- 5.8 years) underwent heart transplantation. Indications for transplantation were idiopathic cardiomyopathy (52%), congenital heart disease (35%) with and without prior repair (71% and 29%, respectively), hypertrophic cardiomyopathy (5%), valvular heart disease (3%), and doxorubicin cardiomyopathy (5%). Patients were managed with cyclosporine and azathioprine. No prophylaxis with antilymphocyte globulin was used. Steroids were given to 39% of patients for refractory rejection, but weaning was always attempted and generally successful (64%). Five patients (14%) received maintenance steroids. Four patients died in the perioperative period and one died 4 months later. There have been no deaths related to rejection or infection. Average follow-up was 36 +/- 19 months (range 1 to 65 months). Cumulative survival is 88% at 5 years. In patients less than 7 years of age, rejection was monitored noninvasively. In the first postoperative month, 89% of patients were treated for rejection. Freedom from serious infections was 83% at 1 month and 65% at 1 year. Cytomegalovirus infections were treated successfully with ganciclovir in 11 patients. No impairment of growth was observed in children who underwent transplantation compared with a control population. Twenty-one patients (60%) have undergone annual catheterizations and no sign of graft atherosclerosis has been observed. Seizures occurred in five patients (14%) and hypertension was treated in 10 patients (28%). No patient was disabled and no lymphoproliferative disorder was observed.(ABSTRACT TRUNCATED AT 250 WORDS)