A population-based case-control study was undertaken to determine whether cutaneous melanoma is associated with past military service in tropical locations. The participants were 150 male residents of southern Queensland aged 50 or over with a first diagnosis of cutaneous melanoma notified to the Queensland Cancer Registry between 1 July 1993 and 30 June 1994; 150 age-matched controls were randomly selected from the Queensland electoral roll. Data were collected from participants using a structured questionnaire. Overall, 82 (55%) cases and 80 (53%) controls reported a period of military service. Of these, 42% of both cases and controls spent part of their military service in tropical locations, with little difference in the distribution of duration of tropical service between the two groups. Compared with those who had no tropical military service, the risk of melanoma among those who had served more than 3 years in the tropics was 0.9 (0.3-2.7). Against a background level of very high risk of melanoma among Queensland men, there was no evidence that tropical military service materially increased the risk.