Between 1980 and 2004, six randomized, controlled trials (RCTs) have been performed to evaluate the width of surgical margin excision for primary cutaneous melanoma and its influence on recurrence and survival. These trials have led to the current recommendation of not more than a 2-cm margin excision and have allowed reduced morbidity of surgery for primary melanoma. Long-term follow-up data has been published which has led to impactful knowledge of the natural history of this disease, yet controversy remains for 1- to 2-mm thickness melanomas. Interpretation of these trials must be done in light of them enrolling patients before the use of sentinel node biopsy and contemporary immunotherapy regimens. These RCTs as well as a contemporary, actively enrolling trial are summarized and discussed in this review.