The oxidative modification of low density lipoprotein (LDL) is thought to play an important role in atherogenesis. Drugs of -hydroxy--methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) family are usually used as a very effective lipid-lowering preparations but they simultaneously block biosynthesis of both cholesterol and ubiquinone Q₁₀ (coenzyme Q), which is an intermediate electron carrier in the mitochondrial respiratory chain. It is known that reduced form of ubiquinone Q₁₀ acts in the human LDL as very effective natural antioxidant. Daily per os administration of HMG-CoA reductase inhibitor simvastatin to rats for 30 day had no effect on high-energy phosphates (adenosin triphosphate, creatine phosphate) content in liver but decreased a level of these substances in myocardium. We study the Cu²⁺-mediated susceptibility of human LDL to oxidation and the levels of free radical products of LDL lipoperoxidation in LDL particles from patients with atherosclerosis after 3 months treatment with natural antioxidants vitamin E as well as during 6 months administration of HMG-CoA reductase inhibitors such as pravastatin and cerivastatin in monotherapy and in combination with natural antioxidant ubiquinone Q₁₀ or synthetic antioxidant probucol in a double-blind placebo-controlled trials. The 3 months of natural antioxidant vitamin E administration (400 mg daily) to patients did not increase the susceptibility of LDL to oxidation. On the other hand, synthetic antioxidant probucol during long-time period of treatment (3–6 months) in low-dose (250 mg daily) doesn't change the lipid metabolism parameters in the blood of patients but their high antioxidant activity was observed. Really, after oxidation of probucol-contained LDL by C-15 animal lipoxygenase in these particles we identified the electron spin resonance signal of probucol phenoxyl radical that suggests the interaction of LDL-associated probucol with lipid radicals in vivo. We observed that 6 months treatment of patients with pravastatine (40 mg daily) or cerivastatin (0.4 mg daily) was followed by sufficiently accumulation of LDL lipoperoxides in vivo. In contrast, the 6 months therapy with pravastatin in combination with ubiquinone Q₁₀ (60 mg daily) sharply decreased the LDL initial lipoperoxides level whereas during treatment with cerivastatin in combination with probucol (250 mg daily) the LDL lipoperoxides concentration was maintained on an invariable level. Therefore, antioxidants may be very effective in the prevention of atherogenic oxidative modification of LDL during HMG-CoA reductase inhibitors therapy.