Abstract: To investigate the effects of alfalfa saponins on cholesterol metabolism and its molecular mechanism, 32 healthy male Sprague Dawley (SD) rats were randomly divided into four groups: normal control group, alfalfa saponins group, hyperlipidemia model group, hyperlipidemia model+alfalfa saponins group. The first four weeks were the hyperlipidemia model establishment period: rats in the normal control group and in the alfalfa saponin group were fed with a basal diet while the other two groups were fed with a high fat diet. The last four weeks were the alfalfa saponins treatment period, alfalfa saponins (240 mg/kg) were administrated to both the alfalfa saponin group and to the hyperlipidemia model+alfalfa saponins group by gavage. The body weight, liver index, serum lipid level, total cholesterol and total bile acids in liver and faeces of the rats were measured. The mRNA expression of CYP7a1 and ABCG5/ABCG8 were measured by real-time PCR. Alfalfa saponins significantly reduced the body weight, liver index and the serum cholesterol level but increased the accumulation of cholesterol in liver and the excretion of cholesterol and bile acids in faeces in hyperlipidemia rats and significantly increased the cholesterol excretion in faeces of normal rats. The mRNA expression of CYP7a1 and ABCG5/ABCG8 were multiplied in the alfalfa saponins treated groups. The results indicated that alfalfa saponins could adjust the distribution of cholesterol in rats and had a significant effect on the decrease of serum lipid. This effect could result from the increasing mRNA expression of CYP7a1 and ABCG5/ABCG8 in liver.