We examined whether or not the gelatinolytic activity in tumor tissue was associated with the invasion and metastasis of oral squamous cell carcinoma (OSCC). Tissue homogenates were prepared from 57 biopsy specimens of OSCC. The gelatinolytic activities in the homogenates were measured by gelatin zymography and its densitometric analysis. The Immnunoblot findings revealed the major gelatinolytic activities to be due to matrix metalloproteinase (MMP)-2 and -9. The zymography-detected gelatinolytic activities of MMP-2 and MMP-9 in the tissue specimens significantly correlated with the degree of immunohistochemical staining detected in frozen sections of the same biopsy specimens. According to a histopathological analysis of the mode of invasion, highly invasive cases showed the increased gelatinolytic activities of MMP-2 as well as MMP-9 in the tissue specimens. Although no significant differences were observed in the gelatinase activities between the metastatic cases and the non-metastatic cases, the levels of tissue inhibitor of MMP (TIMP)-1 in the tumor tissue specimens were higher in the non-metastatic cases than in the metastatic cases. The cases with the high levels of MMPs and low levels of TIMP-1 thus seemed to have a high potential to metastasize. As a result, the zymographic measurement of the gelatinolytic activity in biopsy tissue specimens may therefore be useful in predicting the behavior and prognosis of OSCC.