Prevention and control of sexually transmitted infections (STIs) has proven effective in reducing HIV infection when treatment is available promptly for symptomatic persons in conditions of an emerging epidemic. Biologically, it is assumed that reduced genital tract inflammation reduces infectiousness for HIV as well as reducing susceptibility in HIV-uninfected persons. Male circumcision has been demonstrated effective in reducing risk for HIV infection in three separate trials from South Africa, Kenya, and Uganda. Global expansion of STI treatment and male circumcision programs are vital tools for control of HIV infection; current evidence is reviewed and research priorities are presented.