OBJECTIVE: To quantify the contribution that AIDS makes to adult mortality in rural South Africa. DESIGN: Demographic surveillance of the population in a rural area of northern KwaZulu Natal province. METHODS: The population and all adult deaths (n = 1021) in 2000 were enumerated. We conducted verbal autopsy interviews with the caregivers of those who died to identify the causes of adult deaths. A validation study of the verbal autopsy diagnoses was conducted on 109 individuals with hospital notes that could be located. Death rates and other mortality indices are both calculated directly and estimated indirectly by the orphanhood method. RESULTS: Mortality in the study area rose sharply in the late-1990s. By 2000 the probability of dying between ages 15 and 60 was 58% for women and 75% for men. AIDS, with or without tuberculosis, is the leading cause of death in adulthood (48%). Injuries, mostly resulting from road traffic accidents or violence, cause 20% of deaths of men aged 15-44 years. In the age group 60 years or more, non-communicable diseases account for 76 and 71% of deaths of women and men respectively. CONCLUSIONS: This population has experienced a sudden and massive rise in adult mortality. This can be accounted for by AIDS deaths. Mortality from non-communicable disease and (among men) injuries is also high. Antenatal HIV seroprevalence continued to rise in rural KwaZulu Natal in the late 1990s, reaching 40% in some clinics in this area. Adult mortality will continue to rise unless effective treatment interventions are introduced.