Abstract: The effect of alfalfa saponins on cholesterol metabolism and the expressions of ACAT-2 and HMG-CoAr in the liver of hyperlipidemia rats was investigated. Forty healthy male Sprague Dawley (SD) rats were randomly divided into four groups: normal (control, A), hyperlipidemia model (B), alfalfa saponins prevention group (C), alfalfa saponins treatment group (D). Except for the controls, rats were fed a high-fat diet for eight weeks. Alfalfa saponins were added by gavage to group C from the first week, and to group D from the fifth week. Body weight, liver index and serum lipid level of the rats were measured. Protein and mRNA expressions of ACAT-2 and HMG-CoAr were measured by enzyme linked immunosorbent assay (ELISA) and real-time PCR methods respectively. 1) The body weight, liver index and serum lipid level of hyperlipidemia rats were significantly reduced, and the fatty degeneration and steatosis in the liver were ameliorated by alfalfa saponins. 2) The protein and mRNA expressions of ACAT-2 in groups C and D were significantly lower than those in group B(P<0.01), but there was no significant difference for HMG-CoAr. In conculsion, alfalfa saponins prevented hyperlipidemia by reducing the expression of hepatic ACAT-2, and by inhibiting the absorption of exogenous cholesterol.