Thirty-one renal transplant recipients, submitted to treatment with cyclosporin in association with other immunosuppressive agents, were also treated for 9 months with two hydroxymethylglutaryl coenzyme A reductase inhibitors, simvastatin (10 mg/day) or pravastatin (20 mg/day), for concomitant hypercholesterolemia and hypertriglyceridemia. Both drugs significantly decreased total cholesterol and triglyceride serum levels, but they did not modify whole-blood trough concentrations of polyclonal and monoclonal cyclosporin or polyclonal/monoclonal cyclosporin ratio. No alterations of the clinical and laboratory parameters investigated were found. The results of this study show the efficacy and safety of hydroxymethylglutaryl coenzyme A reductase inhibitors in the treatment of hyperlipidemia in kidney transplant patients.