Policosanol, a new cholesterol-lowering agent, is a mixture of higher aliphatic primary alcohols isolated from sugar cane (Saccharum officinarum L.) wax, which prevents the onset of espontaneously and experimentally induced atherosclerotic lesions in experimental models. Because the oxidation of low-density lipoprotein (LDL) may play a role in the pathogenesis of atherosclerosis, we investigate the effect of policosanol on copper oxidative susceptibility of rat lipoprotein fractions (VLDL + LDL). Rats fed normal diet were treated with policosanol (250-500 mg/kg/day) for up to 4 weeks. EDTA-free lipoprotein particles were oxidized in a cell-free system by the addition of copper ions, and conjugated dienes generation was monitored by changes of optical density at 234 nm. Thiobarbituric acid-reactive substances (TBARS) content and lysine-amino group reactivity were investigated. After administration, there was no change in cholesterol, triglycerides, and phospholipid content of lipoprotein fractions; however, policosanol significantly prolongs the lag time and reduces the propagation rate of diene generation. Also, policosanol reduces TBARS content and increases lysine reactivity in lipoprotein fractions treated with Cu2+. In conclusion, policosanol, in addition to its cholesterol-lowering effect, has other properties that enables it to reduce the potential of lipoprotein to undergo lipid peroxidation. Such effect can be considered of promissory value in the management of atherosclerosis.