Until recently, the problem of traumatic brain injury in sports and the problem of performance enhancement via hormone replacement have not been seen as related issues. However, recent evidence suggests that these two problems may actually interact in complex and previously underappreciated ways. A body of recent research has shown that traumatic brain injuries, at all ranges of severity, have a negative effect upon pituitary function, which results in diminished levels of several endogenous hormones, such as growth hormone and gonadotropin. (...) This is a cause for concern for many popular sports that have high rates of concussion, a mild form of TBI. Emerging research suggests that hormone replacement therapy is an effective treatment for TBI-related hormone deficiency. However, many athletic organizations ban or severely limit the use of hormone replacing substances because many athletes seek to use them solely for the purposes of performance enhancement. Nevertheless, in the light of the research linking traumatic brain injury to hypopituitarism, this paper argues that athletic organizations’ policies and attitudes towards hormone replacement therapy should change. We defend two claims. First, because of the connection between TBI and pituitary function, it is likely many more athletes than previously acknowledged suffer from hormone deficiency and thus could benefit from hormone replacement therapy. Second, athletes’ hormone levels should be tested more rigorously and frequently with an emphasis on monitoring TBI and TBI-related issues, rather than simply monitoring policy violations. (shrink)