Few studies have examined the consequences of the high prevalence of diabetes in Aboriginal communities. We aimed to determine the rates and causes of mortality in all Aboriginal central Australians with diagnosed diabetes, identified by a previous study (n =374). Cohort members were followed from 1 January 1984, or the date of diagnosis (to 31 December 1986), to 31 December 1991 or death. Death certificates, medical notes and autopsy reports were examined for cause of death. There were 130 deaths in 2280.7 person-years of follow-up. Standardised mortality ratios for Aboriginal people with diabetes, compared to the Northern Territory Aboriginal population, were 209 (95 per cent confidence interval (CI) 158 to 273) for men and 169 (CI 129 to 218) for women. The difference in ratios for men and women was not statistically significant when adjusted for age (P = 0.2). The eight-year survival rates for men and women diagnosed between 1984 and 1986 were 55.8 per cent (CI 32.6 to 73.7) for men and 80.3 per cent (CI 64.8 to 89.5) for women. Renal disease was the direct cause of death in 22.3 per cent. Infection accounted for 20.8 per cent of deaths and ischaemic heart disease for 13.8 per cent. Forty-four per cent of death certificates made no mention of diabetes. Diabetes confers an additional risk of death on a population whose mortality is already markedly worse than that of other Australians. Unlike Western diabetic populations, infections and renal disease were more common causes of death than macrovascular disease. Diabetes amplifies the effect of the community prevalence of infection and renal disease.