The influence of Epimedium-derived phytoest rogen flavonoids( EF) on serum E2 level,endometrial thickness and bone mineral density( BMD) of ovariectomy mice is studied.36(4 month-old) female C57 mice are selected and divided into three groups randomly.After 4 weeks,their serum E2 level,BMD of first lumbar vertebrae are measured by quantified CT after execution,and endomet rial thickness is measured by making pathological section after hysterectomia.Index shows that:control group artif operation,model g roup ovariectomy placebo,observ action group ovariectomy+ EF.Compared with control group,the BMD of the observation groupdeclines slightly,while the model group obviously.The serum E2 level of both the model group and the observation group reduces noticeably,so the endomet rial thicknesses of the two g roups are lower compared with the control group.How ever,there is no invisible difference between these two groups.EF has preventive and therapeut icaction to the osteoporosis of mice,which happen following the hypoest rogenemia after ovariectomy,without influence on serum E2 level and endomet rium.