Aim To observe the influence of simvastatin on tumor necrosis factor α(TNF-α)-induced expression of metalloproteinase-9(MMP-9)in human umbilical vein endothelial cell(hUVEC)and to investigate the non-lipid mechanisms of 3-hydroxy-3-methyl-glutaryl coenzyme A(HMG-CoA)reductase inhibitors on anti-atherosclerosis. Methods The expression of MMP-9 in protein level and mRNA level was detected with immunohistochemistry and reverse transcription polymerase chain reaction(RT-PCR). Results TNF-α could induce the expression of MMP-9 in hUVEC.Simvastatin could inhibit the expression of MMP-9 and their inhibitory effects were concentration-dependent and time-dependent. Conclusion The inhibition of TNF-α-induced MMP-9 expression in hUVEC by simvastatin may crucially contribute to the clinical benefits of HMG-CoA reductase inhibitors on coronary artery disease,independent of cholesterol-lowing effects.