Fifty-four patients from August 1975 to March 1980 were treated with high dose per fraction (0-7-21) radiotherapy for malignant melanoma. The patients were subdivided into three clinical subtypes of disease: microscopic residual melanoma following surgery (22 patients), gross residual melanoma following surgery (nine patients), and recurrent melanoma (23 patients). Eighteen of 22 (82%) of patients treated for microscopic residual disease have been free of local recurrence to date. Ten of the 18 are alive and free of disease for up to 44 months following irradiation. Seven of nine (78%) patients treated for gross residual tumor have had no recurrence or progression of tumor in the irradiated volume, five of the nine achieved a complete remission and three are alive and free of disease at ten, 13, and 42 months, respectively. Twenty-three patients with recurrent melanoma were irradiated. Nine achieved a complete remission (39%) of tumor in the irradiated volume and three are alive and free of disease at up to 56 months following irradiation treatment. Three major complications of irradiation have been seen in the 54 patients treated. It is concluded that nodular melanoma is not a radioresistant tumor, large dose per fraction radiotherapy produces a high response rate of patients with measurable disease which is prolonged in some patients. The indications for radiotherapy in nodular melanoma are discussed and prospective studies of irradiation in melanoma are proposed.