Hypopituitarism is an increasingly recognized complication of traumatic brain injury that can have significant potential to impair recovery and rehabilitation in affected survivors. Although posttraumatic cranial diabetes insipidus is known to be transient in many cases, recovery of established anterior pituitary hormone deficiency is thought to be a very rare event. We report the case of a 25-yr-old man who incurred severe traumatic brain injury in 1997. Sixteen months later, dynamic pituitary stimulation tests revealed severe growth hormone and adrenocorticotropin hormone deficiency. He was treated with recombinant human growth hormone and hydrocortisone. Five years after traumatic brain injury, repeat neuroendocrine assessment, prompted by an increasing serum insulin-like growth factor-1 level, showed normal growth hormone and adrenocorticotropin hormone responses. This is the first case report, to our knowledge, to show that adult posttraumatic growth hormone deficiency can be reversible. The recognition that anterior pituitary dysfunction can recover after traumatic brain injury has implications for the follow-up of patients with hypopituitarism secondary to head trauma to avoid unnecessary, expensive, and potentially harmful therapy.