Objective Puerariae Radix (PR) is one of the earliest and most important crude herbs used in Chinese medicine for various medicinal purposes.PR contains a high amount of isoflavonoids such as purerarin,daidzein and genistein,which are known to prevent bone loss induced by estrogen deficiency.We have firstly demonstrated that PR not only completely prevents bone loss,but also significantly increases the bone mass at high doses in ovariectomized mice without exhibiting estrogenic action in the uterus.