Serum levels of lipids and lipoproteins were examined in individuals with hyperlipidemia treated with atorvastatin or colestimide and in healthy volunteers. Modified low-density lipoprotein (LDL) was measured by its faster electrophoretic mobility and expressed as charge modification frequency (CMF). Serum levels of total cholesterol (t-chol), triglyceride (TG), very low-density lipoprotein (VLDL)-chol, low-density lipoprotein (LDL)-chol, and CMF were significantly higher in hyperlipidemia, but there was no significant difference in serum high-density lipoprotein (HDL)-chol levels between hyperlipidemic and healthy subjects. Treatment with atorvastatin resulted in significant decreases of serum t-chol, TG, and LDL-chol levels but not serum HDL-chol and VLDL-chol. Treatment with colestimide significantly reduced serum t-chol, HDL-chol, and LDL-chol levels but not those of TG and VLDL-chol. CMF was significantly reduced by treatment with atorvastatin but not by colestimide. Atorvastatin significantly reduced plasma levels of thrombomodulin, thrombin antithrombin complex (TAT) and tissue type plasminogen activator-plasminogen activator inhibitor-I complex. Colestimide moderately prolonged activated partial thromboplastin time and reduction of TAT. Based on its actions of lowering modified LDL and improving hemostatic abnormalities, we postulate that atorvastatin might inhibit the onset of ischemic diseases.