Metastasis is the most frequent cause of death in patients with breast cancer. The nm23-H1 and p53 genes have been involved in the development of breast cancer metastasis. We have analyzed the correlation between the expression of nm23 protein and several established clinicopathologic factors. Our results show that the antimetastatic role of nm23-H1 is not related to the cell proliferative status or tumor grade and that it is not associated with the expression of p53. We also demonstrate a strong inverse relationship between the expression of nm23-H1 protein, lymph node metastasis and vascular invasion. These data support the antimetastatic role of the nm23-H1 gene and suggest that nm23-H1 and p53 genes may be involved in different steps of the metastatic process.