Objective To investigate the dose-dependent effect and the molecular mechanisms of daidzein on osteoporosis in the ovariectomized rats,and safty of uterus and lacteal gland.Materials and methods Sixty four-month-old Sprague-Dawley (SD) female rats were allotted to one of six groups.Four weeks after reproducing the osteoporosis model of ovariectomized SD rats,Sham group and control OVX were administrated with distilled water,whereas the other groups received valerate estriol (800 μg/kg·d) and different doses of daidzein (10,50,200 mg/kg·d) by gavage respectively for three months.These parameterswere measured after the sacrifice of the rats.