We evaluated highly active anti-retroviral therapy (HAART) use and risk behaviors among 177 inmates who were HIV infected and were released and reincarcerated in San Francisco, Calif, jails over a 12-month period. During the month preceding reincarceration, HIV transmission risk behaviors were common among respondents, and 59% of those with a history of antiretroviral use were not taking HAART. HAART discontinuation was independently associated with homelessness, marijuana use, injection drug use, and not receiving community medical care. Postrelease interventions for inmates who are HIV infected are needed.