Axillary dissection provides important prognostic information and maintains local control in the axilla, but is not generally felt to contribute to the cure of breast cancer. Sentinel node biopsy has the potential to accurately identify node-negative women, allowing axillary dissection to be limited to women with positive nodes who are likely to benefit from the procedure. However, whether complete dissection is needed when a positive sentinel node is identified is uncertain, and this issue is being addressed in a clinical trial. Sentinel node biopsy has also raised the possibility of improving the staging of breast cancer through the detection of micrometastasis. At present, the prognostic significance of small cell clusters detected by immunohistochemistry is uncertain, and definitive information should be forthcoming from ongoing clinical trials. Better stratification of prognostic groups has the potential to allow the more selective use of adjuvant systemic therapy. © 2001 Harcourt Publishers Ltd.