The trial, the largest clinical trial to date, will see 3,000 HIV-negative men and women receive a vaccine containing copies of three HIV genes. Volunteers will not receive the full copy of the HIV virus, making it impossible to be infected in the trial.
Previous trials of the vaccine found it to be safe in stimulating cellular immune responses against HIV.
"Our best hope of ending the Aids epidemic is a safe and effective vaccine," said Elias Zerhouni, director of the National Institute of Health (NIH), which is supporting the trial.
"To achieve that goal requires the concerted effort of governments, scientists and private industry as well as participation by well-informed volunteers."
Trials throughout South Africa are being conducted by the South African Aids Vaccine Initiative (SAAVI) and the HIV Vaccine Trials Network (HVTN). The trial will be double blind, meaning both the researchers and the participants will not know whether they have received the vaccine or a placebo.
In addition to receiving the vaccine, study participants will also receive counselling to reduce the risk of acquiring HIV and condoms.
According to the UN programme on HIV and Aids (UNAids) southern Africa "remains the epicentre of the global Aids epidemic".
UNAids statistics for last year suggest that 18.8 per cent of South Africans between the ages of 15 and 49 are infected with HIV
source In the news UK