This study was designed to determine the most cost-effectiveness strategy for implementation of the 100 percent condom use program. The objectives was to estimate the number of HIV cases averted by each intervention to estimate costs of the alternative interventions to estimate costeffectiveness of the alternative interventions
to calculate for each intervention the probability of being cost-effectiveness and being optimal. The results indicated that the cost-effeotiveness ratio for the 100 percent condom use program that provided for only street-based female sex workers was US 03 per one HIV infection averted, and for both street-based and karaoke-based female sex workers was US 03 per one HIV infection adverted. These two interventions were the cost-effective strategies in comparison to the treatment of one HIV positive case. In conclusion, while the two categories of female sex workers are often not simple to distinguish, the 100 percent condom use program provided to all kind of female sex workers appears to be the most optimal strategy.