Objective: To study angiogenesis of the axillary lymph node metastases including micrometastases in breast carcinoma and the relationship between microvessel density (MVD) and metastasis. Methods: Thirty-seven breast cancer tissues and 121 metastatic axillary lymph nodes were collected from the patients and studied immuno-histochemically. MVD was counted by means of microvideo system under 100 magnification. The diameter of each micrometastasis was measured with a micrometer. Results: The mean diameter of 13 micrometastatic foci was 210± 37 m m. No blood vessel formation was found. MVD of the primary tumor and that of metastatic tumor in the axillary lymph node were 93.8± 21.8 and 89.3± 18.4, respectively (P<0.05). The distribution of microvessels of the metastatic tumor in the lymph node and that of the primary tumor was similar, being higher at the periphery than at the center. Conclusion: Micrometastatic foci of breast carcinoma in the axillary lymph node do not have new blood vessel formation. Their further growth, however, depends on neo-angiogenesis. Treatment based on inhibition of angiogenesis may be efficacious in the prevention of micrometastatic foci from developing into metastatic tumor in lymph node.