OBJECTIVE To investigate the expression of urokinase-type plasminogen (uPA), its inhibitor-1 (PAI-1) mRNA and its protein in human gastric cancer and to find out the relationship among the tumor differentiation, angiogenesis, and other clinical pathologic factors.METHODS In situ hybridization (ISH) was used to get the uPA, PAI-lmRNA in 110 cases with human gastric cancer in 2-tissue microarray (TMA). Immunohistochemical staining (S-P method) for uPA, PAI-1 protein and CD34 were performed in the 110 cases in 2 TMA.RESULTS The expression of the uPA, PAI-lmRNA and their protein happened in the cytoplasm of gastric cancer cells were induced by the poor differentiation of the GC, and the expression of uPA had an increasing trend while the expression of the PAI-1 had a decreasing trend. The microvessel density (MVD) had a positive correlation with the clinical stages and the significant relationship with the lymph node metastasis (P < 0.05). The MVD in uPA positive group was significantly higher than those in uPA negative group (P < 0.05). The expression of PAI-1 has no correlation neither with the clinical stages nor the lymph node metastasis.CONCLUSION The uPA play an important role in invasion and metastasis of GC through promoting angiogenesis. Interdicting the secretion and function of the uPA may allow the target therapy against the tumor invasion. As a new high-throughput technology the tissue microarray is a valuable way to be used in clinical treatment.