Objectives: The purpose of this study was to investigate the effects of Hyolbuchukeo-tang extracts on the hyperlipidemia rats induced by high fat diet. Methods and Materials: In vitro; The extracts prepared for Hyolbuchukeo-tang by hot water extraction (HH), fermentation(HF) and UMPM extraction(HU) method. The extracts were examined for levels of polyphenol compounds, antioxidant activities, and inhibitory potencies for HMG-CoA reductase. In vivo; Sprague-Dawley male rats of weighing $150{pm}5g$ were randomly divided into six groups ; normal control diet(NC), and high fat diet(HC), high fat diet with treated lovastatin of 10mg/kg(PC), high fat diet with Hyolbuchukeo-tang extracts; HH, HF and HU treated extracts of 300mg/kg, respectively. Also, we compared the effects of the extracts of HH, HF and HU on rats fed high fat diet for four weeks. Results: 1. The content of polyphenol compounds and electron donating abilities(EDAs) was the HF higher than HH and HU. The superoxide dismutase(SOD)-like activities were proportionate in consistency and they appeared highly from all extracts. The HMG-CoA reductase inhibition activities was highest activities in the HU. 2. The activities of serum GOT and GPT were significantly lower in the HH and HF groups. The level of serum triglyceride was significantly decreased in the HF group. HH and HU groups were significantly decreased in the atherogenic index(AI). The total cholesterol concentration in liver was significantly decreased in the HF group, and HU showed more significantly decreased in the triglyceride than of the lovastatin. Also, photomicrographs of liver tissue showed higher fat accumulation in the HC group than in the HH, HF and HU groups. Conclusions: These result suggest that the hyper-lipidemia caused by a high fat diet was effectively inhibited the administration of HF and HU.