Abstract: We analyzed forensic autopsy findings of 66 consecutive patients with fatal closed head injury who survived up to 48 days after trauma to ascertain the causal factors and the time course of development of posttraumatic pituitary lesions. Pituitary lesions were identified in 27 patients. In patients with pituitary lesions, posterior lobe hemorrhage was observed in 21 patients, followed by anterior lobe hemorrhage in 10 patients and anterior lobe infarct in 7 patients. Comparisons between patients with and without pituitary lesions showed that falls and subdural hematoma were significantly frequent in patients with pituitary lesions. Immunohistochemistry of neurophysin showed increased immunoreactivity in the hypothalamus of patients with pituitary lesions and brain edema, providing morphologic evidence of pituitary dysfunction. Hemorrhage in the anterior or posterior lobe was identifiable in patients with short survival periods, whereas infarct in the anterior lobe appeared in patients surviving at least 14 hours. These data further our understanding of the mechanisms of pituitary dysfunctions and help in the estimation of the survival period after head trauma.