Abstract: Few studies have examined long-term mortality following traumatic brain injury (TBI) in a military population. This is a secondary analysis of a prospective, longitudinal study that examines long-term mortality (up to 10 years) post-TBI, including analyses of life expectancy, causes of death and risk factors for death in service members and veterans (SM/V) who survived the acute TBI and inpatient rehabilitation. Among 922 participants in the study, the mortality rate was 8.3% following discharge from inpatient rehabilitation. The mean age of death was 54.5 years, with death occurring on average 3.2 years after injury, and with an average 7-year life expectancy reduction. SM/V with TBI were nearly 4 times more likely to die compared with the US general population. Leading causes of death were external causes of injury, circulatory disease, and respiratory disorders. Also notable were deaths due to late effects of TBI itself and suicide. Falls were a significant mechanism of injury for those who died. Those who died were also more likely to be older at injury, unemployed, non-active duty status, not currently married, and had longer post-traumatic amnesia, longer rehabilitation stays, worse independence and disability scores at rehabilitation discharge, and a history of mental health issues prior to injury. These findings indicate that higher disability and less social supportive infrastructure are associated with higher mortality. Our investigation into the vulnerabilities underlying premature mortality and into the major causes of death may help target future prevention, surveillance, and monitoring interventions.