Sixteen subjects with familial hypercholesterolaemia were randomly assigned to treatment with simvastatin 20-40 mg/day (an inhibitor of 3-hydroxy-3-methylglutaryl CoA reductase) or with bezafibrate 600 mg/day (a clofibrate analogue) for 12 weeks. Both drugs produced significant reductions in serum and LDL cholesterol; mean percentage fall -30.5% and -38.1% (simvastatin) and -17.8% and -20.6% (bezafibrate), respectively. Both drugs also caused a decrease in VLDL cholesterol, while only bezafibrate decreased the serum and VLDL triglyceride levels and increased HDL cholesterol and serum apolipoprotein A-I and A-II levels. Serum apolipoprotein B fell by 33.3% (simvastatin) and 15.7% (bezafibrate). Simvastatin and bezafibrate produced significant increases in the mean fractional esterification rate of LCAT, by +124.1% and +20.6%, respectively. Thus simvastatin was clearly more effective than bezafibrate in lowering LDL by enhancing its turnover, but bezafibrate had specific effects on VLDL and HDL that might be favourable in combined treatment regimens.