Among several factors which have been evaluated for prognostic significance in patients with some types of solid tumors, tumor angiogenesis is reportedly correlated with metastasis, relapse, and prognosis of the tumor. Many studies have suggested that tumor growth is angiogenesis-dependent and that besides an increase in the delivery of nutrients to the tumor cells, this neovascularization also increases the opportunity for tumor cells to enter the circulation, which would imply the importance of tumor angiogenesis to the metastatic potential of tumors. The aim of this study was to investigate the correlation between the degree of angiogenesis and the malignancy potential in gastric carcinomas to determine whether angiogenesis of tumors has prognostic significance. Tumor angiogenesis at the invasive margins of 103 paraffin sections of gastric carcinomas was assessed by a immunohistochemical study by using a monoclonal antibody against the factor-VIII-related antigen and was compared with conventional clinicopathologic factors. In addition, the rate and the mode of recurrence were analyzed according to the degree of angiogenesis. Vessels were immunostained with anti-factor VIII polyclonal antibody, and areas with the most discrete microvessels were counted in a 200xfield, which were defined as angiogenesis score. The angiogenesis score from patients with lymph-node metastasis was significantly higher than that from patients without (P=0.0015). Furthermore, the recurrence rate was significantly greater in the group with higher than the mean angiogenesis score (P=0.004), and according to the pattern of recurrence, angiogenesis of tumors with hematogenous metastasis tended to be greater than that with other types of recurrence (P=0.0002). This retrospective study demonstrates that angiogenesis expressed as an angiogenesis score may be a good prognostic indicator and may be useful as a predictor of recurrence in patients with gastric carcinomas. If these findings are confirmed in larger prospective studies, it might be possible to add the angiogenesis score to the prognostic factors used to identify patients at higher risk for recurrence and to guide in decision for more aggressive adjuvant therapy after surgery.