A 4-year study (Japan Neurotrauma Data Bank) of the medical treatment of 1002 cases of traumatic brain injuries in Japan was conducted from 1998 to 2001 at 10 emergency medical centers. Patients with severe head injury were eligible for entry with a Glasgow Coma Scale score of 8 or less at admission. Patients who underwent craniotomy were also included. Children under 5 years old were excluded. An original data sheet with 392 items from multi-focal viewpoints, such as etiology of injury, pre-hospital care, initial treatment including neuro-intensive care unit, and surgical treatment, was created. The results show that the patient's age and mechanism of injury are the most important factors in the outcome.