Objective：To investigate PTP4A1 gene expressions in human tongue squamous cancer tissues and TCA8113 cell line and to explore the relationship between PTP4A1 expressions and clinicopathological features of human tongue squamous cancer. Methods：Expressions of PTP4A1 in 30 cases of human tongue squamous cell carcinoma and 15 cases of normal tongue mucosa paraffin-embed－ded specimens were examined by immunohistochemical technology and in 15 freshly-taken tongue squamous tissues and TCA8113 cells by real-time PCR. Results：Immunoreactive staining was located in the cytoplasm and cell nucleus of human tongue squamous cancer. Positive rate of PTP4A1 in human tongue squamous cancer was 83%，which was remarkably higher than that in normal tongue tissue 33.3%（P=0.001<0.05），with significant differences. Expression of PTP4A1 was closely related with lymphatic metastases（P=0.014<0.05），but had no relationship with age，gender，tumor size，and clinical stage. Result of real-time PCR also showed that PTP4A1 mRNA level was higher in human tongue squamous cancer tissues and TCA8113 cells than in para-carcinoma and normal tissues（P=0.000<0.05）. Conclusions：Both PTP4A1 mRNA and protein expressions are higher in human tongue squamous cancer tissues than in para-carcinoma and normal tongue tissues. PTP4A1 expression may play a significant role in human tongue squamous cancer develop－ment and metastases.