Plasminogen activator(PA) system such as urokinase plasminogen activator(uPA), urokinase PA Receptor(uPAR), tissue, tissue PA, and PA inhibitor-1&2(PAI-1&2) play a role in tumor invasion, metastasis, and proliferation. It is interested that these factors in patients with primary oral squamous cell carcinoma(Oral SCC) will be evaluated and correlated with clinicopathologic variables. Recently, these expression of primary oral SCC has been restricted to clinical or immunohistochemical study such in vivo study. The purpose of this study were to investigate the mRNA expression and cytologic concentration of uPA, uPAr, tPA, and PAI-1,2 in oral SCC cell lines compared to NHOK and to apply these results to evaluate early detection biomarkers of oral SCC in future. All the cell lines(NHOK, HN 4 and SCC 25) were cultured under KBM bullet kit at 37℃ in a 5% CO2 incubator. We studied a possible association between mRNA expression and cytosolic concentrations of uPA, uPAR, tPA, and PAI-1,2 in oral SCC cell lines compared to NHOK using RT-PCR and an enzyme-linked immunoassay(ELISA) method. uPA mRNA expression was about 5-6 folds, while uPAR was a bout 3 f olds, and PAI-1 was about 1 .5-1.6 f olds. PAI-2 was a bout1.2 -1.3 f olds t han that o f NHOK, w hile t PA w as l ower t han that of NHOK. uPA cytosolic concentrations was about 15-19 folds, while uPAR was about 8 folds, and PAI-1 was about 3-4.5 folds. PAI-2 was about 2 folds than that of NHOK, while tPA was lower than that of NHOK. Both uPA, uPAR, and PAI-1,2 cytologic concentrations were correlated with mRNA expression of oral SCC cell lines. From the aboving results, high cytosolic concentrations of uPA, uPAR, and PAI-1 & 2 were correlated with mRNA expression. It suggested that these might be specific markers for oral SCC cell lines and these results would be contributed to evaluate early detection biomarkers for human oral squamous cell carcinoma.