Axillary lymph node dissection is in theory of both therapeutic and prognostic benefit for patients with breast cancer. For several authors, its therapeutic function, which consists in surgical dissection of potentially metastatic nodes, may be assured effectively by radiotherapy, but results of different comparative studies are contradictive. However, axillary dissection should be eliminated for small tumors (< 5 mm) because of the low yield of positive nodes (< 3%). Even if new histologic prognosticators are currently in evaluation, axillary node stagging is the single most important prognostic variable, and determines the indication for chemotherapy for premenopausal patients. Morbidity remains high, even if rarely severe, and new technologies are studied to try to locate the first node draining the tumor, in order to pick it out electively for histologic examination.