The most common endocrine defects associated with head injuries are those involving the posterior lobe of the pituitary gland. The clinical manifestations in these cases are either diabetes insipidus or the syndrome of inappropriate ADH secretion (SIADH). The article describes four cases with posttraumatic failure of the anterior lobe, two of whom also suffered diabetes insipidus. Although hypothalamic and pituitary damage are well known from autopsies, relatively few cases of post-traumatic failure of the adenohypophysis have been published. The mechanism, site of lesion, diagnostic evaluation and follow-up are discussed.