Abstract: Objective To study the effects of EMPs on expression of bone formation-related gene of rat bone marrow stromal cells culutured in vitvo by RT-PCR. Methods Enamel matrix proteins extracted from porcine permanent tooth buds by acidic extraction. Marrow of tibiae and femurs from 3-week-old male SD rats were obtained and cultured in vitro. Well-grown cells at passage 3 were cultured with different concentrations of EMPs(0, 25,50,100,200 mg/L). MTT assay was performed to evaluate the proliferation of BMSCs. The expression of bone formation-related genes BSP, OPN and COL-Ⅰwere detected by RT-PCR. Results Cell proliferation in experimental group was higher than that in control group (P<0.05), and the proliferation was highest when concentration of EMPs was 100 mg/L. The mRNA expression of bone-related genes （BSP、COL-Ⅰ）in experimental group was higher than that in control group, and was in a concentration dependent manner. But, there was no difference between the control group and the experimental group in mRNA expression of OPN gene. Conclusion EMPs enhance osteoblastic differentiation of rat BMSCs by regulation of bone formation-related gene expression.