The study sample included 879 IDU's in Dayton and Columbus, Ohio. Most subjects were black males and had at least a high school education. The majority reported some type of involvement with the criminal justice system; 87.6 percent had spent time in jail. Data were collected via personal interviews using the nationally standardized AIDS Initial Assessment questionnaire developed by the National Institute on Drug Abuse. Interviews lasted 1-2 hours and participants were compensated for their time. Blood samples were collected to determine HIV serostatus. It was found that several HIV high-risk variables significantly correlated with IDU time in jail: drug injection at an early age; multiple sex partners; history of sexually transmitted disease; daily drug use; daily injection of cocaine, heroin, or speedball; inconsistent condom use; and use of rented needles. Active IDU's with the highest HIV risk behaviors were those most likely to spend time in jail. The authors conclude that the criminal justice system should implement drug and AIDS prevention programs and that public health initiatives on HIV risk behaviors should receive priority in correctional institutions. 34 references and 5 tables