Sentinel lymph node (SLN) biopsy is a useful way of assessing axillary status and obviating axillary dissection in patients with node-negative breast cancer. A combination of dye- and gamma probe-guided methods can identify SLN more accurately and easily than either of these techniques alone. On the other hand, SLN biopsy is highly accurate and sensitive in patients with small tumors, and no false-negative SLN biopsy has been reported for a breast cancer < 1.0-1.5 cm. Moreover, extensive intraoperative examination of SLNs using frozen sections can attain a sensitivity comparable to that obtained by histologic examination on the permanent sections. In practice, therefore, axillary dissection can be avoided in patients with small tumors in whom the SLNs are negative.