OBJECTIVE: To study the effects of Simvastatin on the osteoblast activity of human periodontal ligament (PDL) cells. METHODS: The third passage human PDL were cultured in conditional mineralization medium with different concentrations of Simvastatin. The cells were divided into A group (0 mol/L), B group (1 x 10(-9) mol/L), C group (1 x 10(-8) mol/L), D group (1 x 10(-7) mol/L) and E group (1 x 10(-6) mol/L). Alkaline phosphatase (ALP) activity, osteopontin (OPN) and capability of mineralization were measured. RESULTS: Differentiation osteoblast and mineralization of human PDL were improved in all treatment groups with different concentrations of Simvastatin (1 x 10(-9), 1 x 10(-8), 1 x 10(-7), 1 x 10(-6) mol/L). Compared with control group, statistically significant differences were found in 1 x 10(-8) mol/L, 1 x 10(-7) mol/L and 1 x 10(-6) mol/L groups (P<0.05). The maximum effect was observed at the concentration of 1 x 10(-7) mol/L. CONCLUSION: Optimal concentration of Simvastatin can improve the osteoblastic activity of human PDL.