Non-fatal overdose among injection drug users (IDU) is a source of significant morbidity. Since it has been suggested that supervised injecting facilities (SIF) may increase risk for overdose, we sought to evaluate patterns of non-fatal overdose among a cohort of SIF users. We examined recent non-fatal overdose experiences among participants enrolled in a prospective study of IDU recruited from within North America's first medically supervised safer injecting facility. Correlates of recent non-fatal overdoses were identified using generalized estimating equations (GEE). There were 1,090 individuals recruited during the study period of which 317 (29.08%) were female. At baseline, 638 (58.53%) reported a history of non-fatal overdose and 97 (8.90%) reported at least one non-fatal overdose in the last six months. This proportion remained approximately constant throughout the study period. In the multivariate GEE analysis, factors associated with recent non-fatal overdose included: sex-trade involvement (Adjusted Odds Ratio [AOR]: 1.45 [95% Confidence Interval [CI] 1.07-1.99], p = 0.02) and public drug use (AOR: 1.50 [95% CI 1.09-2.06]; p = 0.01). Using the SIF for >or= 75% of injections was not associated with recent non-fatal overdose in univariate (Odds Ratio: 1.05, p = 0.73) or multivariate analyses (AOR: 1.01, p = 0.96). The proportion of individuals reporting recent non-fatal overdose did not change over the study period. Our findings indicate that a sub-population of IDU might benefit from overdose prevention interventions. Our findings refute the suggestion that the SIF may increase the likelihood of overdose.