Objective To investigate the effect of Nifedipine on matrix metalloproteinase（MMP）-10 and MMP-13 expression in human periodontal ligament fibroblast（HPDLF） induced by mechanical strain in vitro. Methods HPDLF was divided into four groups at random by mechanical strain of elongation 0%, 8%, 12% and 16%. Each group was divided into four subgroups again by the concentration of Nifedipine 0, 10, 30, 50 μm. The cells were imposed to state mechanical strain 12 h after incubated with Nifedipine 1 h. And then immunohistochemical staining was used to investigate the expressions of MMP-10 and MMP-13 in intracytoplasm. Results In 0% group, there was no significant difference of MMP-10 and MMP-13 expression in all subgroups（P>0.05）. The expressions of MMP-10 and MMP-13 were high in group 8%, 12% and 16% without Nifedipine, and increasing significantly with elongation（P
