Tumor angiogenesis(TA) refers to the growth of new vessels toward and within a tumor. TA is necessary both at the beginning and at the end of the metastatic cascade of events. Recently, experimental evidence suggests that the growth of a tumor beyond a certain size requires angiogenesis. To investigate how tumor angiogenesis correlates with metastases in breast carcinoma, the microvessels were counted (per 200 / field) in the most active areas of neovas-cularization by two investigators. The microvessels within breast carcinoma were highlighted by in imunohistochemical staining for factor VIII-related antigen. Microvessel count(MVC) in node-positive carcinoma(59.66=35) was significantly higher than in node-negative carcinoma(44.76=17)(p=0.009). MVC was also statistically correlated with tumor size and stage, but not with histologic grading, DNA ploidy, or hormonal receptors(estro-gen and progesterone). MVC in invasive breast carcinoma may be one of many prognostic predictors of node-positive breast carcinoma. Assessment of tumor angiogenesis may therefore be valuable in selecting patients with early breast carcinoma for aggressive therapy.