Cyclooxygenease-2 (COX-2) expression is a critical factor in inflammation, and plays an important role in defense against exogenous stimuli, while overexpression of COX-2 causes cells to exhibit changes in tumor phenotype. This article attempted to determine the mechanisms underlying the chemopreventive effects of celecoxib on cellular level events, in order to characterize the effects of celecoxib with regard to human oral squamous cell carcinoma (OSCC) cell growth and invasion/migration. In order to determine COX-2 expression levels, we used an OSCC cell line established from surgically resected specimens of an untreated primary OSCC of the tongue, and used reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses with anti-COX-2 monoclonal antibodies. The YD-10B cells represented a highly invasive OSCC cell line, which was found to express the COX-2 protein. Celecoxib inhibited the growth of this OSCC cell line, in a time- and dose-dependent manner. This reduction in cell proliferation was associated with the upregulation of the cyclin-dependent kinase (CDK) inhibitors, p27. In addition, 10 uM celecoxib inhibited cell invasion/migration through the type I collagen matrix by approximately 40% within 24 h. The results of zymography reveal that, in the presence of 10 muL celecoxib, both MMP-2 and MMP-9 enzyme activity decreased by approximately 30-40%. The current in vitro study indicated that the inhibition of proliferation and invasion/migration in OSCC cell line by the COX-2-specific inhibitor, celecoxib, results in anticancerous effects via a variety of cellular and molecular mechanisms. This article also supports the notion that the COX-2 inhibitor may be useful in the inhibition and/or prevention of metastasis.