BACKGROUNDRadiotherapy is not used commonly in the treatment of patients with malignant melanoma. The benchmark optimal radiotherapy utilization rates for melanoma are largely unknown, despite the fact that melanoma is a very common cancer.METHODSTo develop an evidence‐based benchmark for the optimal proportion of patients with melanoma who should receive radiotherapy, the authors reviewed major treatment guidelines for melanoma. A radiotherapy decision tree was constructed showing the clinical features of melanoma patients for whom radiotherapy was indicated based on evidence. The proportions of melanoma patients with indications for radiotherapy were obtained from epidemiologic data and were used to calculate the optimal proportion of melanoma patients who should receive radiotherapy.RESULTSThe proportion of patients with melanoma for whom radiotherapy is indicated at some point in their illness, according to the best available evidence, was calculated at 23% of all melanoma patients. The utilization rates of radiotherapy for melanoma recorded in actual practice were 13% in New South Wales, 6% in data from the American College of Surgeons, and 1% according to Surveillance, Epidemiology, and End Results data.CONCLUSIONSStrategies for implementing the evidence‐based guidelines are recommended to overcome the shortfall in the use of radiotherapy in the treatment of patients with melanoma. Cancer 2004. © 2004 American Cancer Society.