Aim To investigate the effect of macrophage colony-stimulating factor(M-CSF) on the expression and activity of matrix metalloproteinases(MMP) in RAW264.7 cell. Methods Gelatin zymography analysis was used to detect the effect of M-CSF on activity of MMP-9 in cultured RAW264.7 cell.Reverse transcription polymerase chain reaction(RT-PCR) was used to detect the effect of M-CSF on expression of MMP-9 mRNA in cultured RAW264.7cell. Results The enzyme activity of MMP-9 was significantly increased after 24 h M-CSF treatment.M-CSF had no effect on the activation of MMP-9 secreted.RT-PCR showed that M-CSF upregulated MMP-9 mRNA expression after 8hour M-CSF treatment. Conclusion M-CSF upregulates MMP-9 expression in RAW264.7 cell,which may play an important role in plaque destabilization.