Correctional staff educators handed out surveys to all inmates at the beginning of AIDS educational courses in 12 prisons between May and December 1993. Comparison groups of prisoners were recruited from the same prisons by surveying general education courses that fell on the same days. A total of 196 surveys were returned, 181 from inmates in AIDS education course (92 percent) and 15 from inmates in general education courses. Analysis was confined to the former group. Overall, 40 percent of the respondents reported HIV risk behavior in prison. One-quarter of the respondents reported injecting, of whom three-quarters reported sharing syringes in prison. Most respondents who shared syringes reported cleaning them with disinfectants (96 percent), even though only one-third reported having easy access to disinfectants. One-sixth of the respondents reported sharing tattooing equipment, of whom two-thirds reported using a disinfectant to clean the tattoo needle. Few respondents reported fellatio (8 percent) or anal intercourse (4 percent) in prison. Although some respondents faced difficulty in obtaining disinfectants, almost all respondents cleaned syringes with bleach when sharing. High levels of risk behavior in prison might be reduced by methadone maintenance and condom programs. A trial of strict one-for-one syringe exchange warrants consideration. 3 tables, 1 figure, and 23 references