Although SLN biopsy is considered standard of care by many surgical oncologists and dermatologists, it remains controversial among others. Clinical practitioners in both surgery and dermatology have used the same available evidence to both support and refute the sentinel lymph node hypothesis and the role SLN biopsy should play in the management of cutaneous melanoma. Much of this disagreement centers on whether one views SLN biopsy as a therapeutic intervention meant to improve survival or a diagnostic test meant to stratify risk and select patients for further therapy. This article will review the available data, including the most recent data from the MSLT-I trial, the first prospective randomized study of SLN biopsy in melanoma.http://deepblue.lib.umich.edu/bitstream/2027.42/51542/1/SLNB for melanoma- therapy or diagnosis.pd