Background/Aims: In the process of tumor invasion, angiogenesis is prerequisite for tumor growth. Many studies have shown that angiogenesis plays an important role in the growth, progression, and metastasis of solid tumors. Recently, several angiogenic factors, angiopoietin 1 (Ang-1) and its naturally occurring antagonist angiopoietin 2 (Ang-2), have been identified. They are novel ligands that bind to the Tie-2 receptor on endothelial cells. Ang-1 activates Tie-2 receptor on endothelial cells to promote recruitment and interaction with support cells such as pericytes and smooth muscle cells. In contrast, Ang-2 reduces matrix contacts and interactions of support cells with endothelial cells, which are necessary for the neovascularization process to occur. Methods: In order to investigate the role of Ang-1 and Ang-2 in invasion and metastasis of the adenocarcinoma of the stomach, 108 cases of gastric adenocarcinomas were selected. These cases include 53 early gastric carcinoma (EGC) and 55 advanced gastric carcinoma (AGC). The specimens were stained with the Ang-1 and Ang-2 antibodies by immunohistochemical staining method. Results: The expression level of the Ang-1 and -2 is statistically correlated with the depth of invasion (T factor) and the lymph node metastasis (N factor) (P<0.001). Both Ang-1 and Ang-2 were more strongly and extensively expressed in AGC than in EGC (P<0.001). Carcinoma cells that metastasized to lymph nodes showed a stronger and more extensive staining pattern than their primary counter part of adenocarcinoma (P<0.001). Conclusions: These results indicate that both Ang-1 and Ang-2 are important in invasion and metastasis of gastric adenocarcinoma.