With data from a surveillance system that uses verbal autopsies to identify cause of death in rural South Africa, we investigated whether mortality from HIV/AIDS differs from other causes of death in its effect on household dependency ratio, and to what extent the effect is mediated by the baseline dependency ratio. Findings: (i) the impact of death from HIV/AIDS on the dependency ratio in 2005 is marginally positive compared with other causes of death, but (ii) the impact is overpowered by the effect of death at working age, and (iii) the baseline dependency ratio mediates the effects on the 2005 ratio of cause of death and of the individual's sex and age at death. Migration into and out of the household—anticipating or responding to a death—seems to be a key source of change in the household dependency ratio.