Axillary nodes status is the best single predictor of disease outcome in patients with breast cancer; presence ofaxillary node metastasis (ANM) reduces the patient's 5-year survival by 28-40%. However, ANM is seen in only 40% of all breast cancer and furthermore since axillary lymph node dissection (ALND) is associated with significant morbidity, sentinel lymph node biopsy (SLNB) seems to be a good alternative for nodal staging in breast cancer. Pathologically negative sentinel lymph node (SLN) is able to predict the absence of metastasis to the remainder of the regional lymph node basin with a very high degree of certainty. This article presents a systematic detailed review of the existing studies on SLNB in relation to the following parameters: sensitivity and accuracy of the different techniques used; pathologic evaluation of SLN; clinical and pathological factors affecting SLN status and role of SLNB in different clinical situations related to breast cancer management. We have also included brief mention of our experience at UMass from a pathological perspective in this review article.