OBJECTIVE--Detailed analysis of primary cutaneous melanoma first diagnosed in Scotland in patients aged 65 and over. DESIGN--Comparison of changing incidence, sex distribution, site, histogenetic type, tumour thickness, and prognosis of all primary cutaneous melanomas in patients aged 65 and over diagnosed in Scotland in the 11 years 1979-89 with similar data for patients aged under 65. SETTING--Data were obtained from the Scottish Melanoma Group's database, established in 1979, which aims to record detailed clinical, pathological, and surgical follow up details of all primary cutaneous melanomas registered in Scotland. PATIENTS--1430 patients (954 women, 476 men) aged 65 and over; comprising over a third of the 3903 patients with primary melanoma recorded for all age groups in Scotland during this period. RESULTS--The overall incidence of melanoma in patients aged 65 and over increased from 12.2/100,000 in 1979 to 20.7/100,000 in 1989, with the greatest increase seen in older men, from 7.8/100,000 in 1979 to 18.0/100,000 in 1989. The site most commonly affected was the face in both men and women (33% of all tumours). The most common histogenetic type was superficial spreading melanoma. 526 patients (37%) had melanomas with a tumour thickness of 3.5 mm or greater in the older age group, compared with 453 patients (18%) in those aged under 65. The highest proportion of thick tumours was seen in older men. Five year survival figures for 616 patients diagnosed between 1979 and 1984 were 88%, 66%, and 47% for thin, intermediate, and thick tumours respectively. Overall five year survival for the older age group was 64% compared with 78% for the younger age group. CONCLUSION--The increase in melanoma in the elderly and the high proportion of thick tumours, especially in men, require a specific educational programme for both primary and secondary prevention directed towards the older population.