Abstract: To investigate the expression and significance of both S100A4 and MMP-9 in normal laryngeal tissues and laryngeal squamous cell carcinoma, and to discuss the roles of S100A4 and MMP-9 and their correlation in the process of laryngeal squamous cell carcinogenesis. Methods: The expressions of S100A4 and MMP-9 were determined using immunohistochemical S-P method. The relationship between the expressions of S100A4 and MMP-9 and their clinical pathological features were analyzed using the Western blot method. Result: The expression of S100A4 and MMP-9 significantly increased in laryngeal squamous cell carcinoma and was correlated with lymphatic metastasis. The immunohistochemical results showed an increasing tendency in the positive rate of S100A4 and MMP-9 expressions from normal laryngeal tissues ( 8.6% and 14.3%, respectively ) as well as from laryngeal squamous cell carcinoma ( 63.8% and 71.3%, respectively ). The Spearman's correlation test revealed that the S100A4 expression was significantly positively associated with MMP-9 expression in the 80 laryngeal squamous cell carcinoma specimens ( P <0.01, rs = 0.440 ). Western blot results showed that expression of S100A4 and MMP-9 protein in laryngeal squamous cell carcinoma tissues was significantly higher than that in the non-tumorous counterparts, and the expression of MMP-9 protein in Hep-2 cells decreased after restraining the S100A4 protein. Conclusion: Both S100A4 and MMP-9 were abnormal in the development of laryngeal squamous cell carcinogenesis, and S100A4 gene suppression significantly decreased the expression of MMP-9.