Few studies have attempted to quantify Islam's contributions to HIV/AIDS prevention. Senegal has involved Muslim leaders in its prevention campaign for over a decade. Senegal also has the lowest HIV/AIDS prevalence rate in sub-Saharan Africa. This study examines how Islam influences AIDS prevention by testing whether Senegalese participants' religiosity scores explain their risky decisions associated with sex, condom use, and drug use. Participants with higher religiosity scores were more likely to abstain from sex. However, participants high in religiosity were not more likely to report that they did not use condoms when sexually active.