The data reveal that prisons have high concentrations of injection drug users (IDUs). Rates of HIV are high among new admissions, and IDUs are the second largest group at risk for HIV infection. High-risk behaviors occur with some frequency within prisons as well. As a result, the rate of HIV infection has been steadily increasing in prisons, although the rate of increase has slowed. Similarly, tuberculosis rates and rates of multidrug-resistant tuberculosis are rising in prison populations. Both these phenomena present risk for infections spread among the inmate population and to the communities to which released inmates return and in which the correctional personnel live. In addition, AIDS and HIV disease and treatment of active tuberculosis involve high medical costs, which corrections or health department budgets will soon be unlikely to meet. Costs of social services, mental health care, and prevention programming increase the costs. Nevertheless, incarceration provides opportunities to deliver HIV prevention services; to test different models for prevention; and to test new vaccines in a relatively controlled setting. Programming needs to develop content that matches the sensitivities and issues of minorities, women, and IDUs at particularly high risk of developing HIV. Recommended actions include making HIV testing and condom distribution be available to all inmates on request and providing post-test counseling and support services for all. Additional recommendations and 52 references (Author abstract modified)