BACKGROUND: It has been suggested that the expression of angiogenic factors by tumor cells contributes to the increased neovascularization and vessel permeability that are associated with tumor vasculature. However, the significance of protein expression involving tumor angiogenesis in gastric cancer has yet not to be classified. METHODS: In this study, the expression of vascular endothelial growth factor (VEGF), cyclooxygenase (Cox), and nitric-oxide synthase (NOS) were investigated in 14 surgically resected human gastric carci nomas by using western blotting. RESULTS: In 6 of 14 paired cases, VEGF expression in the tumor tissue was slightly increased compared with the nonneoplastic counterpart in the same specimen. However, the expression of inducible-type Cox-2 was significantly increased in tumor tissue while the expression of constitutive-type Cox-1 was decreased. The expression of endothelial-type eNOS in cancer tissue was shown to be higher than in normal gastric resected tissues, but the expression of nNOS in cancer was lower than it was in a normal gastric mucosa. CONCLUSION: Although a direct positive correlation between VEGF expression and cyclooxygenase or nitric oxide synthase was not found in differnt stages of gastric tumor development, the cyclooxygenase and nitric-oxide synthase may play an important role in gastric cancer development.