The inhibitory effects of the traditional herbal medicine Hwao-tang on the progression of the atherosclerotic lesions were studied using the spontaneous familial hypercholesterolemia (FH) model, Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits. Hwao-tang is activate blood circulation, vital energy and regulate menstruation, etc. Nowadays, Hwao-tang is mainly used for the treatment of inflammation, hyperlipemia and arteriosclerosis. However, pharmacological mechanisms of Hwao-tang on lipid metabolism and atherosclerosis formation are poorly understood. We have investigated the pharmacological effects of Hwao-tang on hypercholesterolemia and atherosclerosis using a spontaneous experimental model. In conclusion, the protection of extracts of HOT and its herbs on the ischemic infarction induced artificially might be related to their inhibitory effects on DIC, platelet coagulation and thrombic action. These suggest that Hwao-tang has inhibitory effects on the development of atheromatous plaque formation in spontaneous FH model rabbits. It is possible that the anti oxidative effects of Hwao-tang on LDL led to the beneficial effects observed in this study.