This article reports on the effectiveness of the first systematically developed health education intervention for the reduction of risky sexual behavior among soon-to-be-released prisoners in South Africa. Data from three out of four prisons are eligible for data analysis including 263 inmates. Using a nested experimental design, short-term evaluation while inmates were still in prison demonstrate that experimental groups showed higher knowledge of sexually transmitted infections and had a more positive intention to reduce risky behavior than the control group in two out of three prisons. Long-term assessment 3 to 6 months after release from prison indicates that experimental groups were more positive about sexual communication, self-efficacy, and intention. Groups educated by an HIV-negative educator perform marginally better than those in groups with an HIV-positive peer educator. It is argued that peer-led health education programs may be effective in reducing risky behavior amongst soon-to-be-released inmates.