In order to investigate the effects of Radix Achyranthis Bidentatae (RAB) on the growth and differentiation of human osteoblast-like cells, we supplemented the culture medium of MG-63 cells with various concentrations of RAB water extracts. RAB extracts significantly stimulated cell growth, as confirmed by the colorimetric MTT (3-dimethylthiazol-2,5-diphenyltetrazolium bromide) assay. RAB extracts also increased the alkaline phosphatase (ALP) activity, which is a osteoblast differentiation marker. These results suggest that RAB can stimulate osteoblastic activity and may represent new pharmacological tools for the treatment of osteoporosis.