Prenylflavonoids and its glycoside derivatives isolated from the Traditional Chinese Medicine (TCM), Epimedium, have potent estrogenic properties. The principal bioactive compounds in Epimedium are the prenylflavonoids, icaritin, and their glycosylated derivatives which can enhance osteoblastic differentiation and mineralization, inhibits bone resorption, and induces apoptosis of osteoclasts. Animal experiments indicate that icariin can prevent bone loss induced by ovariectomized (OVX) in rats, through its stimulatory effects on osteoblast growth and function, and inhibitory action on osteoclast cells.