Background Blunt thoracic aortic injuries (BTAIs) can be lethal, but advances in trauma systems and surgical care have helped reduce mortality. The purpose of this study is to investigate whether time from injury to presentation is associated with mortality following BTAI. Methods Using the Ontario Trauma Registry, all patients were identified who were hospitalized with BTAI between 1999 and 2009. Variables including age, sex, Injury Severity Score, Charlson comorbidity index, systolic blood pressure on admission, operative intervention, and time from injury to presentation were analyzed using multivariate logistic regression to determine independent predictors of mortality. Results We identified 264 cases of BTAI that survived until hospital admission. Of these, 220 patients had documented time from injury to presentation to hospital. Most, 68.2% (n = 150), presented within 60 min of injury. On adjusted multivariate analysis, a prehospital time of ≤60 min independently predicted higher mortality (odds ratio 0.27, 95% confidence interval 0.08–0.89, P = 0.03). Tight clustering was seen with prehospital time and mortality. Conclusions Rather than reducing mortality as hypothesized, a shorter time between BTAI and hospital presentation (<60 min) is associated with increased mortality. This may be the result of selection bias with the quicker transport of more severely injured patients.