Objective: To investigate the expression and clinical significance of proteinase activated receptor-1(PAR-1) in oral tongue squamous cell carcinoma(OTSCC). Methods: Real-time RT-PCR was used to characterize the expression of PAR-1 mRNA in 15 samples of OTSCC. The expression of PAR-1 protein in 109 tumor tissue samples including with peritumoral tissue from patients with OTSCC was detected with immunohistochemisty. Results: RT-PCR and immunohistochemisty showed that the expression of PAR-1 in OTSCC was significantly higher than that in the tumor-adjacent non-malignant tissues (P < 0.01). And the statistical analysis of clinicopathologic characteristics and immunohistochemistry showed that the high expression of PAR-1 protein in OTSCC was related to diameter of tumor and the later of stage grouping with TNM classification (P = 0.035 and P = 0.015,respectively). In contrast,no statistically significant correlation was found for gender and age. Kaplan-Meier survival and Cox regression analyses also showed that high PAR-1 expression and stage grouping with TNM were independent poor prognostic factors for OTSCC patients. Conclusion: The expression of PAR-1 protein was related with malignant level of OTSCC cancer. PAR-1 could be used as a mark of clinical prognosis and a potentially therapeutic target of OTSCC.