BACKGROUND: The role of the single matrix metalloproteinases (MMPs) in the metastatic process of squamous cell carcinomas (SCC) is still obscure. MATERIALS AND METHODS: The MMP-9 expression was described immunohistochemically in 105 patients (40-79 years of age, mean: 57.84 years; 84 male, 21 female) suffering from orophatyngeal cancer (22x TI, 31x T2, 24x T3, 28x T4) with different neck stages (41x N0, 6x N1, 54x N2, 4x N3 neck). RESULTS: A significant correlation between MMP-9 expression and T stage (p <0.05), N stage (r = 0.55, p <0.01) and UICC stage (r = 0.55, p <0.01) was revealed. Most remarkable was the high MMP-9 expression with simultaneously high UICC stages. CONCLUSION: The results give further indication that MMP-9 plays a role in the metastatic behavior of oropharyngeal SCC. It will be a project for the near future to create a standardized evaluation score of immuno-histological stainings to allow valid comparison of the results and published data.