Abstract: Objective: To investigate the significance and relationship between matrix metallopro-teinase 9 (MMP-9) and infiltration of macrophage in the process of invasion and metastasis in oral squamous cell carcinoma (OSCC). Methods: The expressions of MMP-9 and CD68 were detected in 42cases of OSCC and 10 cases of normal tissues by immunohistochemical SABC method. CD68 was usedto detect macrophages specifically. Results: The level of MMP-9 expression and the ratio of macrophages in OSCC samples both were significantly higher than that in normal tissues (P<0.05). Thelevel of MMP-9 expression and the counting of macrophages were correlated with lymph-node metasta-sis and TNM stage (P<0.05) they showed positive correlation (γ =0.443) with statistic significance (P<0.01). Conclusion: Both MMP-9 and macrophages may play an important role in the process of inva-sion and metastasis of OSCC and higher level of MMP-9 expression in OSCC tumor may be resulting from the macrophage infiltration.