Lymph node involvement is considered to be one of the most important independent prognostic factors in breast cancer. In patients without palpable lymphadenopathies, the method of choice for determining this involvement is the sentinel lymph node biopsy. In the presence of macrometastases, the current standard is to perform axillary lymph node dissection in spite of the knowledge that the involvement of non-sentinel lymph nodes is approximately 50%. When lymph node involvement is micrometastasic, the decision as to whether or not to proceed with lymphadenectomy remains in dispute. We set out, on the basis of the current scientific evidence and our own experience, to create guidelines that allow us to individualise each case and decide whether or not to perform a lymphadenectomy. We will discuss the arguments that support our position.