The current study describes the significance of supplemental magnesium for brain protection after traumatic brain injury .In this study, 300 adult patients with mild, moderate or severe traumatic brain injury were randomly assigned one of two doses of magnesium or placebo within 8 h of injury and continuing for 5 days. Magnesium doses were targeted to achieve serum magnesium range of 4.0 mEq/L. The outcome was a composite of mortality, seizures, time of stay in hospital and functional measures assessed up to 6 months after injury. The conclusion was that “Parenteral magnesium sulphate by intravenous infusion within the first 8 hours after bolus dose in head trauma for the first 5 days trying to keep serum level of magnesium around 4 mEq/L appears to improve survival, reduce early and late seizures, shorten period of hospital stay in all patients with traumatic head injury, and is associated with better favorable outcome and less disability at 6 months in patients with GCS 9-12, without any apparent significant adverse effects.