Background: Traumatic brain injury (TBI) still remains a difficult disorder to treat. TBI has been associated to chronic neuroinflammation and a high risk for neurodegenerative disorders. Since 2001 between ten to twenty percent of all deployed military members have suffered a combat-related TBI. Nearly twenty to thirty percent of those will experience chronic cognitive, behavioral and somatic symptoms after suffering a TBI. Methods: The objective of this review is to evaluate current literature examining vitamin D as a neurosteroid with protective properties and its clinical relevance after traumatic brain injury. Vitamin D is known to participate in neurobiological processes and genomic regulation in the brain. Clinical and laboratory findings support that vitamin D modulates the immune responses to trauma, diminishes oxidative and toxic damage, and inhibiting activation and progression of the neuroinflammation. Inadequate levels of vitamin D have been identified as a common risk factor for many neurological disorders and have been linked to poorer recovery. Results: This review found compelling evidence to support that the pathology of TBI is closely associated with neuroprotective mechanisms of vitamin D. Low vitamin D levels are common among US active duty military and veterans. The findings strongly suggest that optimizing vitamin D prior to injury could improve the recovery for military members after experiencing a TBI. Vitamin D ameliorates brain damage by modulating neuroinflammation, improving cell survival and down-regulating mechanisms involved in the progression of cell damage following a TBI. However, further studies are needed to evaluate the effects of vitamin D optimization in TBI outcomes.