On Nov 1, 1984, an orthotopic cardiac transplantation was performed in an 8-month-old female infant with subendocardial fibroelastosis. Because of the advanced state of cardiac failure, the operation was done despite a positive tissue crossmatch for antitoxic donor-specific antibodies. Immunosuppression consisted of high doses of cyclosporine (up to 550 mg/m2 or 30 mg/kg) and steroids. Hypertension and tremor of the extremities, which were attributed to cyclosporine, occurred during the first week but resolved after seven days. No signs of nephrotoxic effects have been noted; however, a severe episode of allograft rejection was detected by endomyocardial biopsy on the seventh postoperative day, and a moderate rejection episode was noted on the 22nd postoperative day. Histologic improvement was seen after treatment with conventional steroid pulses. The patient was discharged on Nov 29, 1984. Complications consisted of four episodes of otitis media caused by Staphylococcus aureus and one rejection episode that was treated on an outpatient basis with an intravenous methylprednisolone sodium succinate pulse. Our experience emphasizes both the feasibility and importance of performing endomyocardial biopsies in infant recipients. Through biopsy, episodes of rejection can be discovered when clinical signs are not yet apparent. Eighteen months after transplantation, the child was developing and growing normally.