Abstract: Objective To investigate the biological effects of the serum of rats fed with kidney-tonifying traditional Chinese drugs on cultured osteoblasts in vitro.Methods The culture media containing the serum from rats fed with the drugs at different doses (high, mediate and low doses) were used to treat the second passage of the osteoblasts from the skull of newborn SD rats, and the cell proliferation, differentiation and mineralization were observed.Results The serum stimulated the cell proliferation, enhanced alkaline phosphatase activity and increased the number of mineralized nodules in the cultured osteoblasts.Conclusion Kidney-tonifying traditional Chinese drugs can stimulate the proliferation, differentiation and maturation of cultured osteoblasts in vitro.