Abstract: Objective : To investigate the correlations among the expression of Ang-2 to the clini-copathologic parameters, microvessel density (MVD) and vessel maturation index (VMI) in OSCC, and evaluated the significance of expression of Ang-2 in association with vascular endothelial cell growth factor (VEGF) in tumor angiogenesis and vessel maturation. Methods : The expression of Ang-2 and of VEGF were studied in 41 cases with OSCCs, 30 paraneoplastic oral tissues and ten normal oral mucosa by conventional immumohistochemistry. MVD and VMI were also assessed with double -labeling immumohistochemistry staining against CD34, a marker of pan -endothelial cells, and that against alpha-smooth muscle actin (-SMA), a marker of mural cells (pericytes/smooth muscle cells). Results : Of the 41 OSCC tissues, 21 (51.22%) Ang-2 were positive. Ang-2 was mainly detected in cytoplasm of OSCC.The expression of Ang-2 was significantly higher in OSCC than in adjacent noncancerous oral tssues (P<0.05) and normal oral mucosa (P<0.01). In the cunicoDathologic parameters, Ang -2 expression was closely correlated with lymph node metastasis of the tumor (P<0.01), but there was no significantly correlation among the Ang-2 expression and patients' sex, age and TNM stages and tumor's differentiated degree (all P>0.05). The MYD of positive-Ang-2 OSCC was significantly higher than that of negative-Ang-2 OSCC (P<0.05) while Y M I of positive-Ang-2 OSCC was significantly lower than that of negative-Ang-2 OSCC (P<0.05). When Ang-2 expression was combinated with the staus of YEGF exprssion, MYD of positive-Ang-2 and positive-VEGF expression were significantly high (51.08±2.99) as compared with that of other status in patient with OSCC (all P<0.05). Conclusion : These results suggest that overexpression of Ang -2 may play a crucial role in the development of OSCC. It is closely associated with angiogenesis and vessel maturation of the tumor.