Introduction: Injured brains have significant biochemical alteration in the form of dyselectrolytemia. Electrolytes have correlation with  response of treatment.

Methods: Forty one head injury patients were included. Serum electrolytes Sodium, Potassium, Calcium and Magnesium were measured in patient of traumatic brain injury on 1^st day and 3rd day of injury. Traumatic Brain Injury (TBI) patients were assessed by using Glasgow Coma Score (GCS).

Result: Serum Sodium, Potassium, Calcium level were found significantly low on day of injury, which improved on day 3. Serum Magnesium concentration was found to be markedly decreased on day 1, but not normalized on 3rd day of TBI. Level of consciousness following head injury is the most important factor in the management of patient of TBI and can be assessed fairly by using GCS.

Conclusion: There is correlation between serum Magnesium level and GCS score, suggesting serum Magnesium may be used as a marker of severity of head injury.