A series of experimental methods including 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide(MTT) test, alkaline phosphatase(ALP) activity measurement, Oil Red O stain and measurement, mineralized function expression and quantitive real time RT-PCR(qRT-PCR) were employed to assess the effects of DyCl3 on the the proliferation, differentiation and mineralization function of primary osteoblasts(OBs) in vitro at cell and molecular levels. The results showed that DyCl3 inhibited the proliferation of OBs at tested concentrations. As to the differentiation of OBs, DyCl3 promoted the differentiation of OBs at concentrations of 1x10(-8), 1x10(-6), and 1x10(-5) mol.L-1. DyCl3 suppressed the adipogenic transdifferentiation of OBs at tested concentrations. DyCl3 promoted the formation of mineralized matrix nodules of OBs at a higher concentration 1x10(-5) mol.L-1, turned to inhibit the formation of mineralized matrix nodules of OBs at concentrations of 1x10(-7) and 1x10(-6) mol.L-1, but had no effect on the formation of mineralized matrix nodules of OBs at a concentration of 1x10(-8) mol.L-1. The expression of the mRNA for PPAR-gamma was significantly down-regulated, the expression of the mRNA for RUNX-2 was up-regulated in the presence of 1x10(-6) mol.L-1 DyCl3. Our experimental results suggest that the effects of DyCl3 on the proliferation,