A total of 452 patients with dysplastic nevi (DN) were followed prospectively by repetitive, complete cutaneous examinations in order to determine the clinical features of early malignant melanomas (MM) arising in them. Sixteen patients (3.5%) developed 18 newly diagnosed MM during an average follow-up period of 27 months. Twelve of the 18 MM were in situ and all of the primary invasive MM diagnosed prospectively in this follow-up were less than 0.89 mm in Breslow thickness, implying an excellent prognosis. The principal clinical clue to the diagnosis of MM was change in a preexisting pigmented lesion. Total-body photographs were very useful in helping to identify the early MM in these patients.