Background: Traumatic brain injury (TBI) is a leading cause of injury-related disability among older adults and there is increasing interest in long-term post-discharge management as this population grows. There is currently a lack of information on the long-term impact of having a TBI among older adults, and this is essential for informing post-injury interventions and policies directed at maintaining their independence and quality of life. Objective: This study evaluated the effect of an isolated TBI on the long-term development of physical and psychological health outcomes in a nationally representative sample of older adult Medicare beneficiaries. Specifically, I evaluated the association between TBI and incident frailty, disability, nursing home (NH) entry, chronic pain, insomnia, depression, anxiety/PTSD. Methods: I conducted a retrospective study of a 5% random sample of U.S. Medicare beneficiaries ≥65 years of age for years 2007-2015. I used cumulative logit regression models with stabilized inverse probability weights to estimate the odds associated with an increase in frailty and disability as a function of injury status over 5 years. I also used Cox proportional hazards models with stabilized inverse probability of exposure weights to model time to nursing entry, chronic pain, insomnia, depression, anxiety/PTSD as a function of injury in the presence of death as a competing risk and generated hazard ratios (HR) and 95% confidence intervals (CI). Results: I identified 207,355 adults aged ≥65 years, diagnosed with either a TBI, non-TBI trauma, or were uninjured between January 2008 and June 2015. The mean age was 77±9 years, 86% were white (n=177,419), and 70% were female (n=144,670). I found that TBI increased the risk of all examined outcomes compared to the general population of Medicare beneficiaries. In addition, TBI increased the risk of frailty, NH placement, depression, and anxiety/PTSD compared to those with non-TBI trauma. Conclusions: Among older adults, TBI was associated with a higher risk of adverse physical and psychological functioning outcomes. My findings suggest that older adults with TBI may benefit from targeted rehabilitation interventions to reduce the occurrence of these outcomes.