Background:There is recent evidence to suggest that sustaining a traumatic brain injury (TBI) increases risk of criminal justice system involvement, including incarceration. The objective of this study was to explore the association between TBI and risk of incarceration among men and women in Ontario. Methods:We identified a cohort of 1.418 million young adults (aged 18-28 yr) on July 1, 1997, living in Ontario, Canada, from administrative health records; they were followed to Dec. 31, 2011. History of TBI was obtained from emergency and hospital records, and incarceration history was obtained from the Correctional Service of Canada records. We estimated the hazard of incarceration using Cox proportional hazard models, adjusting for relevant sociodemographic characteristics and medical history.Results: There were 3531 incarcerations over 18 297 508 person-years of follow-up. The incidence of incarceration was higher among participants with prior TBI compared with those without a prior TBI. In fully adjusted models, men and women who had sustained a TBI were about 2.5 times more likely to be incarcerated than men and women who had not sustained a TBI.Interpretation: Traumatic brain injury was associated with an increased risk of incarceration among men and women in Ontario. Our research highlights the importance of designing primary, secondary and tertiary prevention strategies to mitigate risk of TBI and incarceration in the population. Abstract ResearchResearch CMAJ OPEN CMAJ OPEN, 4(4) E747