The first HIV/AIDS vaccines are likely to be expensive and limited in supply, and developing countries with generalized HIV/AIDS epidemics will need to distribute the limited vaccine stock in a manner that is both efficient and practical. This analysis compares seven strategies for distributing an HIV/AIDS vaccine in different South African sub-populations, using a mathematical model. If vaccination is not coupled with HIV screening, vaccination of 16-year olds in school is likely to be the most efficient strategy for averting HIV infections in the short term. If coupled with screening, vaccination of sex workers and patients seeking STD treatment would be more efficient, but these gains in efficiency would have to be weighed against the practical challenges associated with vaccinating 'high risk' groups and conducting screening.