A review of sexual abstinence programmes has found that most do not prevent young members from taking sexual risks.
An analysis of 13 trials with 15,900 participants found that abstinence programme members were no more likely to abstain from unprotected sex than anyone else.
Abstinence-only programmes also failed to effect when individuals lost their virginity, their number of sexual partners, pregnancy rates and the spread of sexually transmitted diseases.
One trial did prevent members from having sex but this was limited to the first month.
The study authors commented in the British Medical Journal: "The trial results also suggest that abstinence only programmes do not effectively encourage abstinent behaviour but instead are ineffective for preventing or decreasing sexual activity among most participants."
Programmes that encourage the use of condoms were found to be much more effective in reducing the risk of HIV.
The authors suggest their data may inform ongoing assessments of federal funded abstinence-only interventions in the USA.
"Sexual abstinence programmes are very important since they highlight aspects of preventing or reducing the risk of HIV. Please bear in mind this could be successful if the individual has never been involved in sexual activities before. It is very important to to encourage the use of condoms and to give lectures on how the infection can enter the body and the spread of it" - Name and address supplied