Objectives To determine the relation between the HIV/AIDS epidemic and support for dependent elderly people in Africa.Design Retrospective analysis using data from Demographic and Health Surveys.Setting 22 African countries between 1991 and 2006.Participants 123â[euro][per thousand]176 individuals over the age of 60.Main outcome measures We investigated how three measures of the living arrangements of older people have been affected by the HIV/AIDS epidemic: the number of older individuals living alone (that is, the number of unattended elderly people); the number of older individuals living with only dependent children under the age of 10 (that is, in missing generation households); and the number of adults age 18-59 (that is, prime age adults) per household where an older person lives.Results An increase in annual AIDS mortality of one death per 1000 people was associated with a 1.5% increase in the proportion of older individuals living alone (95% CI 1.2% to 1.9%) and a 0.4% increase in the number of older individuals living in missing generation households (95% CI 0.3% to 0.6%). Increases in AIDS mortality were also associated with fewer prime age adults in households with at least one older person and at least one prime age adult (P<0.001). These findings suggest that in our study countries, which encompass 70% of the sub-Saharan population, the HIV/AIDS epidemic could be responsible for 582â[euro][per thousand]200-917â[euro][per thousand]000 older individuals living alone without prime age adults and 141â[euro][per thousand]000-323â[euro][per thousand]100 older individuals being the sole caregivers for young children.Conclusions Africa's HIV/AIDS epidemic might be responsible for a large number of older people losing their support and having to care for young children. This population has previously been under-recognised. Efforts to reduce HIV/AIDS deaths could have large "spillover" benefits for elderly people in Africa.