In the sentinel lymph node era, axillary lymph node dissection (ALND) for uninvolved axillary lymph nodes should be considered unnecessary and inappropriate. Between January 2000 and August 2005, 3487 out of 10,031 invasive breast cancer patients consecutively operated at the European Institute of Oncology were considered not suitable for sentinel lymph node biopsy (SNB) and were directly submitted to ALND ('direct ALND'). In 2875 cases (82%) a variable grade of axillary involvement was shown, while in 612 patients (18%) no evidence of metastatic spreading was documented in the axilla. In particular, the presence of suspicious nodes at pre-operative clinical evaluation of the axilla (191 patients), neoadjuvant treatment (188 patients), large tumour >2 cm (88 patients), multifocality of disease (76 patients), previous excisional biopsy (49 patients), were considered the most frequent contraindications to SNB and led to an 'unnecessary ALND'. According to the wider extension of the indications for SNB over the time, the number of 'unnecessary ALNDs' progressively decreased from 26% (in 2000) to 9% of the 'direct ALNDs' (in 2005). As the clinical indications to SNB are progressively extending to encompass most breast cancer patients with non-metastatic disease who were previously excluded, great effort should be made to avoid 'unnecessary ALNDs'.