The initial application of intraoperative lymphatic mapping and sentinel lymphadenectomy followed by selective complete lymphadenectomy (LM/SL/SCLND) was in melanoma. This arose as a solution to the ongoing debate concerning immediate vs. delayed lymph node dissection. Acceptance of the concept and advances in nuclear medicine, surgery, and pathology aspects of the sentinel node procedure have brought it into widespread use for melanoma and have expanded its application for other solid tumors that progress through the lymphatic route. Although the diagnostic accuracy of the procedure has been demonstrated in multicenter trials, caution should be exercised regarding therapeutic aspects until definitive benefit can be shown from well-designed clinical trials. Current issues of active discussion and debate are reviewed including ideal nomenclature, clinical significance of occult metastatic disease, quality assurance, and the role of LM/SL/SCLND outside high-volume melanoma centers.