The surgical treatment of patients with cutaneous melanoma has been revolutionized by the development of lymphatic mapping and sentinel lymph node biopsy. This procedure involves injecting a radioactive tracer at the site of the primary melanoma (before wide excision); the tracer then travels via the lymphatics to the first draining or sentinel lymph node. The node is removed and evaluated for the presence of metastatic melanoma. In this way, patients who are most likely to benefit can be selected for regional lymphadenectomy. In addition, accurate and minimally invasive staging allows the surgeon to identify patients who may benefit from adjuvant and investigational immunotherapy. We review the development of lymphatic mapping, the technical details related to the procedure itself, and the published clinical studies using this new procedure. In addition, we discuss the controversial issues that have been raised with the introduction of sentinel lymph node biopsy.