Beginning in the early 1990’s, the Ministry of Correctional Services in Canada began to have concerns about the prevalence of HIV infection among inmates. This concern led to a focus on injection drug use activity among inmates and the need for inmate drug treatment services. In this study, the authors add to the knowledge about injection drug use among inmates in Canada by interviewing 439 adult males and 158 adult females incarcerated in 6 provincial correctional facilities in Ontario, Canada. Participants were questioned about their lifetime drug use and their drug use while incarcerated. Multiple regression analysis was used to determine the independent correlates of injection while incarcerated among the 32 percent of the original sample who had a prior history of injection drug use. Among the entire sample, 45 percent had a history of lifetime drug use. Among those with a prior history of injection, 11 percent reported injecting during the past year of incarceration. Independent correlates of injection while incarcerated were prior history of injection, not injected with used needles, and ever being incarcerated in a Federal prison. The authors conclude that the risk of HIV infection within Canadian correctional facilities exists and that injection while incarcerated is correlated with prior injection history. As such, the Canadian correctional system is called upon to provide more aggressive drug treatment services to inmates. Tables, references