The results of treatment of 42 cases of lentigo maligna and 16 of lentigo maligna melanoma at the New York University Medical Center was reviewed. The recurrence rate after surgical excision of 22 lesions of lentigo maligna was 9% (2/22), but after treatment of 20 such lesions with destructive techniques (X rays, curettage-electrodesiccation, cryosurgery), it was 35% (7/20). Of 11 cases of lentigo maligna melanoma that were excised, none recurred locally, but fatal metastases ensued in one case. Five patients who were eventually classified as having lentigo maligna melanomas had been treated by destructive techniques. In four of them there were local recurrences and in two, metastases as well; the fifth patient had metastases without local recurrence. On the basis of this review of these 58 cases, we conclude that surgical excision and careful histologic study of step sections through the entire lesion insure accurate diagnosis and provide the highest cure rates for lentigo maligna and lentigo maligna melanoma.