The high prevalence of hypercholesterolemia in kidney transplant recipients probably contributes to the high cardiovascular mortality in these patients. Except for diet, there is no generally recommended cholesterol-lowering treatment. We conducted a double-blind, randomized, placebo-controlled study with low-dose simvastatin in 40 ciclosporin (CS)-treated kidney transplant recipients during 16 weeks, focusing on side effects and dose finding. In the simvastatin group, the mean serum total and LDL cholesterol concentrations decreased by 23 and 33%, respectively, and the mean serum HDL cholesterol concentration increased by 12%, after 4 weeks of treatment with simvastatin 10 mg daily. Increasing the dose to 20 mg daily in a few patients only resulted in marginal further reductions of the serum cholesterol concentrations at the expense of doubling the plasma simvastatin 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitory activity concentrations. The differences between the changes in the serum cholesterol concentrations in the simvastatin group and the negligible changes in the placebo group were statistically significant. There was no case of proximal myopathy and the serum creatine kinase concentrations did not differ between treatment groups. In conclusion, low-dose simvastatin appears to be a well tolerated and efficacious cholesterol-lowering treatment in CS-treated kidney transplant recipients. Simvastatin 10 mg daily seems to be the most suitable dose for the majority of these patients.