Chemokines have been initially characterized as chemoattractants for leukocytes infiltrating into inflamed tissues. However, over the past few years, accumulating evidence has described the critical involvement of this superfamily of intercellular signaling proteins in a variety of biological processes, which include embryogenesis, organogenesis, and tissue homeostasis. Moreover, recent work has demonstrated novel roles for chemokines and their receptors in regulating various aspects of the transformed phenotype, such as tumor growth, angiogenesis, invasion, and metastasis. Here, we review the current knowledge regarding chemokine/chemokine receptor involvement in breast cancer pathogenesis with primary emphases on their role in the metastatic spread of cancer cells and in tumor-stroma interactions.