Plasma-oxidized (ox) low-density lipoprotein (LDL) is an atherogenic lipoprotein. The distribution of ox-LDL in plasma LDL subfractions and the effect of statins on this distribution have not been investigated in detail. We examined the distribution of cholesterol and ox-LDL in 3 ultracentrifugally separated plasma LDL subfractions and investigated the effects of a statin, rosuvastatin, on the levels of these lipoproteins. Thirty-one polygenic hypercholesterolemic subjects were included in this study. Levels of cholesterol and ox-LDL in 3 plasma LDL subfractions and plasma levels of remnant-like particle cholesterol, ox-LDL, and adiponectin were measured after 0, 3, 6, and 12 months of treatment with rosuvastatin. Sequential ultracentrifugation was performed to subfractionate plasma lipoproteins. The mean daily dose of rosuvastatin over the 12 months of treatment was 2.9 ± 1.0 mg (mean ± standard deviation). The cholesterol subfraction distribution was 43 ± 10% as low-density LDL, 46 ± 8% as medium-density LDL, and 13 ± 5% as high-density LDL. Similarly, the distribution of ox-LDL was 31 ± 10% as low-density LDL, 48 ± 7% as medium-density LDL, and 22 ± 8% as high-density LDL. After 12 months of treatment with rosuvastatin, the level of cholesterol was significantly reduced in all 3 subfractions (P < .0001), as was the level of ox-LDL (P < .0001). Furthermore, the plasma cholesterol level in high-density lipoprotein2 increased significantly. The distribution of ox-LDL in plasma LDL subfractions was more skewed toward the denser subfractions, compared with cholesterol. Rosuvastatin treatment significantly reduced plasma levels of cholesterol and ox-LDL in all LDL subfractions.