BackgroundPeople recently released from prison engage with emergency healthcare at greater rates than the general population. While retention in opioid agonist treatment (OAT) is associated with substantial reductions in the risk of opioid-related mortality postrelease, it is unknown how OAT affects contact with emergency healthcare. In a cohort of men who injected drugs regularly prior to imprisonment, we described rates of contact with ambulance services and EDs, and their associations with use of OAT, in the 3 months after release from prison.MethodsSelf-report data from a prospective observational cohort of men who regularly injected drugs before a period of sentenced imprisonment, recruited between September 2014 and May 2016, were linked to state-wide ambulance and ED records over a 3-month postrelease period in Victoria, Australia. We used generalised linear models to estimate associations between OAT use (none/interrupted/retained) and contact with ambulance and EDs postrelease, adjusted for other covariates.ResultsAmong 265 participants, we observed 77 ambulance contacts and 123 ED contacts over a median of 98 days of observation (IQR 87–125 days). Participants who were retained in OAT between prison release and scheduled 3-month postrelease follow-up interviews had lower rates of contact with ambulance (adjusted incidence rate ratio (AIRR) 0.33, 95% CI 0.14 to 0.76) and ED (AIRR 0.43, 95% CI 0.22 to 0.83), compared with participants with no OAT use postrelease. Participants with interrupted OAT use did not differ from those with no OAT use in rates of contact with ambulance or ED.ConclusionWe found lower rates of contact with emergency healthcare after release among people retained in OAT, but not among people reporting interrupted OAT use, underscoring the benefits of postrelease OAT retention. Strategies to improve accessibility and support OAT retention after leaving prison are important for men who inject drugs.