OBJECTIVE Beliefs about HIV treatment effectiveness and the impact of HIV treatments on HIV transmission risks were initially related to sexual risk-taking in the late 1990s when multidrug HIV treatments first became available. This study examined changes in beliefs about the effects of HIV treatment for preventing HIV transmission and their association to sexual risk behaviors between the years 1997 and 2005. METHODS Anonymous surveys were administered to a convenience sample of gay and bisexual men attending a large community event in Atlanta, Georgia in 1997 (N = 498) and again at the same community event in 2005 (N = 448). Analyses were performed for men living with HIV/AIDS and for men who have not been diagnosed with HIV/AIDS. METHODS Rates of unprotected anal intercourse in the previous 3 months. RESULTS There were significant increases in high-risk sexual practices that coincided with increased beliefs that HIV treatments can reduce the chance of transmitting HIV. However, optimistic beliefs about the health benefits of HIV treatments decreased over the 8 years and were not related to risk behaviors. CONCLUSIONS Beliefs about how HIV treatments impact HIV infectiousness remain associated with HIV transmission risk behavior and interventions targeting at-risk as well as HIV-positive men who have sex with men must directly address these beliefs and perceptions.