To examine the effects of cardiac transplantation on skeletal maturation and linear growth, we retrospectively evaluated annual bone age determinations and growth parameters of pediatric cardiac transplant recipients followed at our center. Included in the analysis were records of 86 patients (32 females) who had received a cardiac transplant at our institution between 1984 and 1998. Bone age delay of > or =12 months was apparent in 38.5% at the time of transplantation. At some point in their post-transplant course, 23 patients (29%) had one or more bone age measurements that were > or =36 months delayed with respect to chronological age. Children transplanted before age seven and those with a pretransplantation diagnosis of cardiomyopathy experienced the most significant decrement in skeletal maturation after transplantation. High cyclosporin A levels and low body mass index were the only parameters found to be associated with delayed bone age. Although the majority of children grew at a normal rate after transplantation, height Z scores and height age were adversely affected regardless of the type of heart disease or the age at transplantation. The pathogenesis of both delayed skeletal maturation and growth retardation in this population warrant further investigation.