The aim of the study was to investigate the atherosclerosis risk factors related to hyperlipidemia in renal transplanted children. Plasma cholesterol, triglycerides, apolipoproteins (Apo) AI, All and B, and the major lipoprotein classes separated by gradient ultracentrifugation were compared in 30 renal transplanted patients and 14 healthy children. Hyperlipidemia was present in 66% of the transplanted children. ‘Positive’ risk factors for atherosclerosis (high plasma cholesterol and Apo B) were present in hypercholesterolemic and combined hyperlipidemic subgroups. All transplanted children, whether normo- or hyperlipidemic, presented essentially ‘negative’ risk factors for atherosclerosis, i.e. significantly higher levels of Apo AI and All in plasma and in high-density lipoprotein HDL2 and higher Apo AI/Apo B and/or Apo AII/B ratios. Repeated evaluations (over a 12-month period) in transplanted children indicated relatively frequent individual changes in the lipid pattern, but not in Apo AI and All content. These results suggest that the risks for accelerated atherosclerosis related to hyperlipidemia may be considered as moderate in transplanted c