Context.-Axillary nodal status remains one of the most important prognostic indicators in the management of breast cancer. Axillary node metastases are seen in fewer than half of breast cancer cases, and axillary lymph node dissection is associated with significant morbidity. Sentinel lymph node biopsy (SLNB) has become the gold standard for axillary staging of breast cancer. Objective.-To present a detailed review of the existing studies on SLNB in relation to the various techniques, the pathologic evaluation of the sentinel node, and special situations that can involve SLNB. We discuss recent trials that have already had an influence on surgical and pathologic management of breast cancer. In this article, we also discuss our practice and experience at UMass Memorial Medical Center, Worcester, Massachusetts, from a pathologic and surgical perspective. Data Sources.-Published articles from peer-reviewed journals in PubMed (US National Library of Medicine). Conclusions.-Sentinel node biopsy has become standard of care in the surgical management of breast cancer, and emerging data show that the survival benefits of axillary lymph node dissection may not be greater than sentinel node biopsy alone in patients with up to 2 positive sentinel nodes. Therefore, there have been recent changes to the role of intraoperative sentinel node evaluation, and an impact on overall breast cancer management.