Immunohistochemical staining for CD9, CD31 and vascular endothelial growth factor (VEGF) was performed in breast carcinoma specimens. CD9 was expressed in the membrane of carcinoma cells in 61 of 93 cases (67%), CD31 in the membrane of carcinoma cells in 23 of 86 cases (27%), and VEGF in the cytoplasm of carcinoma cells in 26 of 86 cases (30%). The expression of CD9, CD31 and VEGF did not singly correlate with any clinicopathological factors. However, a loss of CD9 with concurrent expression of CD31 or VEGF in the invasive component showed a slight correlation with lymph node metastasis. These findings suggest that the potential for metastatic spread to lymph nodes in breast carcinoma may be synergically affected by various factors.