We investigated the relationship between abnormalities of physiological parameters and clinical outcome in patients with severe head injury. The results were then compared with those of the previous project (Project 1998) reported by Tokutomi and Shigemori. The data for 1101 patients enrolled in the Japan Neurotrauma Data Bank were studied. Of these patients, those with a Glasgow Coma Scale (GCS) score of 9 or more, cardiopulmonary arrest, under 9 years of age, and for whom physiological data were incomplete were excluded. This left a total of 556 patients. Hypoxia and hypoxia at admission were seen in 5% and 10% of the patients, respectively, thus accounting for a lower proportion of patients relative to those reported in Project 1998. Hyperglycemia was associated with a poorer outcome, similar to the results obtained in Project 1998. Hypothermia and hyperthermia on admission were not associated with outcome. The influence of multiple trauma (abbreviated injury score ≥ 3) on the examined parameters was almost the same as that observed in Project 1998. Intracranial pressure (ICP) was monitored in only 31% of the patients, the proportion being lower than that (35%) in Project 1998. To improve patient outcome, the lessons learned from both projects should be applied practically.