Hyperlipidemia is a common problem in solid organ transplant recipients. In this study we evaluated the role of pre-transplant renal replacement therapy on early and late changes of serum lipid levels in children following renal transplantation. In 46 children with chronic renal failure (median age 10.3 years) and 12 children with heart failure (median age 5.0 years), cholesterol and triglycerides were measured before and during follow-up after transplantation. Children with renal failure had significantly higher serum lipids than controls ( n=34, median age 9.2 years) and patients with heart failure. Pre transplantation, cholesterol and triglycerides were significantly lower in the hemodialysis than in the peritoneal dialysis population, whereas conservatively treated children had intermediate levels. After transplantation, serum cholesterol converged towards a mean level of 208 mg/dl and triglyceride levels converged towards a uniform level of 195 mg/dl at 9 months post transplant. The ratio of cholesterol/high-density lipoprotein significantly decreased from 4.7 to 3.8. The pattern of "post-transplant hyperlipidemia" was similar in both renal and cardiac allograft recipients. Hence, the early post-transplant changes of serum lipid pattern are markedly dependent on the mode of pre-transplant renal replacement therapy. Later, serum lipid levels were no longer influenced by prior renal replacement therapy and showed a new pattern of "post-transplant hyperlipidemia" in all children.