Recent studies have demonstrated the importance of neuroendocrine disorders and their potential impact on recovery after traumatic brain injury. These studies suggest that dysfunction of various endocrine pathways is extremely common, occurring in 50% or more of TBI survivors. Additionally, most studies suggest that there is poor correlation between severity of injury and the presence of these abnormalities. Several clinical trials are currently underway to investigate the efficacy of hormone replacement therapy for dysfunction of various hormone systems. This symposium will review the basic science background for the importance of this area, and discuss several clinical trials that have been completed or are underway on hormone therapy after TBI.