Although sentinel lymph node (SLN) biopsy for melanoma has been adopted throughout the United States and abroad as a standard method of determining the pathologic status of the regional lymph nodes, some controversy still exists regarding the validity and utility of this procedure. SLN biopsy is a minimally invasive procedure, performed on an outpatient basis at the time of wide local excision of the melanoma, with little morbidity. Numerous studies have documented the accuracy of this procedure for identifying nodal metastases. There are four major reasons to perform SLN biopsy. First, SLN biopsy improves the accuracy of staging and provides valuable prognostic information for patients and physicians to guide subsequent treatment decisions. Second, SLN biopsy facilitates early therapeutic lymph node dissection for those patients with nodal metastases. Third, SLN biopsy identifies patients who are candidates for adjuvant therapy with interferon alfa-2b. Fourth, SLN biopsy identifies homogeneous patient populations for entry onto clinical trials of novel adjuvant therapy agents. Overall, the benefit of accurate nodal staging obtained by SLN biopsy far outweighs the risks and has important implications for patient management.