IntroductionEpidemiologic studies have shown that people released from correctional facilities are at substantially increased risk of overdose-related death compared with the general population. However, the reported effect estimates are substantially heterogeneous, and the previous studies have important limitations in relative risk assessment for overdose-related death. Objectives and ApproachBritish Columbia, Canada, has experienced an unprecedented epidemic of drug overdose, this study aimed to investigate how the overdose epidemic has affected formerly incarcerated persons. A 20% random sample of residents aged 18 years or older in British Columbia was used to conduct this cohort study. During the 5-year exposure period (January 2010 to December 2014), persons with an incarceration history were identified using provincial incarceration records. During the 3-year follow-up period (January 2015 to December 2017), overdose-related deaths were identified using linked administrative health data. Risk of overdose-related death was compared between persons who did and did not have an incarceration history using a Cox regression model. ResultsOf 765,690 persons in the cohort, 5,743 had an incarceration history during the exposure period, and 634 died from drug overdose during the follow-up period. The mortality rate was 832 and 22 per 100,000 person-years for persons who did and did not have an incarceration history, respectively. Compared with persons without an incarceration history, and adjusting for individual and neighbourhood characteristics, persons who had an incarceration history were 3.67 times (95% confidence interval 2.93 - 4.59) more likely to die from drug overdose. This association was stronger for females, persons who did not have substance use disorder, and persons who were not dispensed opioids for pain or benzodiazepines. Conclusion/ImplicationsPrevious incarceration is strongly associated with risk of overdose-related death. Specific interventions are needed to better prevent drug overdose for people released from incarceration.