The standard surgical treatment of the axilla in patients with early breast cancer is about to undergo a radical change. Although axillary dissection is an excellent procedure for both staging and local control, particularly in the clinically positive axilla, it has considerable morbidity and may understage a significant proportion of patients, because it will usually miss micrometastases that can occur in approximately 10% of ‘node negative’ patients. An increasing number of patients whose tumours are either non-invasive (ductal carcinoma in situ; DCIS), micro-invasive, tubular cancers or low-grade T1a tumours without lymphovascular invasion may be spared axillary surgery because the risk of axillary disease is 0–3%. Many studies, both prospective trials and large retrospective series, show that axillary radiotherapy alone provides similar local control rates to axillary dissection in patients with clinically negative axillas. Primary treatment of the axilla with radiotherapy alone, however, does not allow appropriate staging. Sentinel lymph node biopsy is being increasingly used in patients with breast cancer to provide this information. When a sentinel node is identified it is equal to or better than axillary dissection for staging the axilla and, if the node is positive, it will help select patients who should then proceed to further axillary surgery or axillary radiotherapy. Although sentinel lymph node biopsy is being rapidly adopted in many centres worldwide, the results of randomized controlled trials are needed before it can be recommended as the standard of care.