BACKGROUND: In Western Europe and elsewhere, medically supervised safer injection facilities (SIFs) are increasingly being implemented for the prevention of health- and community-related harms among injection drug users (IDUs), although few evaluations have been conducted, and there have been questions regarding SIFs' ability to attract high-risk IDUs. We examined whether North America's first SIF was attracting IDUs who were at greatest risk of overdose and blood-borne disease infection. METHODS: We examined data from a community-recruited cohort study of IDUs. The prevalence of SIF use was determined based on questionnaire data obtained after the SIF's opening, and we determined predictors of initiating future SIF use based on behavioral information obtained from questionnaire data obtained before the SIF's opening. Pearson's chi-square test was used to compare characteristics of IDUs who did and did not subsequently initiate SIF use. RESULTS: Overall, 400 active injection drug users returned for follow-up between December 1, 2003 and May 1, 2004, among whom 178 (45%) reported ever using the SIF. When we examined behavioral data collected before the SIF's opening, those who initiated SIF use were more likely to be aged <30 years (odds ratio [OR]=1.6, 95% confidence interval [CI]=1.0-2.7], p=0.04); public injection drug users (OR=2.6, 95% CI=1.7-3.9, p<0.001); homeless or residing in unstable housing (OR=1.7, 95% CI=1.2-2.7, p=0.008); daily heroin users (OR=2.1, 95% CI=1.3-3.2, p=0.001); daily cocaine users (OR=1.6, 95% CI=1.1-2.5, p=0.025); and those who had recently had a nonfatal overdose (OR=2.7, 95% CI=1.2-6.1, p=0.016). CONCLUSIONS: This study indicated that the SIF attracted IDUs who have been shown to be at elevated risk of blood-borne disease infection and overdose, and IDUs who were contributing to the public drug use problem and unsafe syringe disposal problems stemming from public injection drug use.