Background and aim: Traumatic brain injury is the second leading cause of mortality in Iran. Understanding the factors affecting the clinical outcomes of these patients can improve the therapeutic results. The aim of this study was to investigate the relationship between sodium and potassium serum levels at admission time and the clinical outcomes in head trauma patients. Methods: This descriptive-analytic study was performed in the Intensive Care Unit (ICU) of Shahid Rajaee Hospital in Qazvin in 2019. In this study, 70 mechanically ventilated head injury patients who met the inclusion criteria were selected by available sampling method. According to the level of sodium on admission day patients were divided into two groups: hyponatremia (sodium <135) and normonatremia (sodium ≥ 135). Also, according to the level of potassium on the day of admission, they were divided into two groups: hypokalemia (potassium>3. 5) and normokalemia (potassium≥ 3. 5). Patients in the hyponatremic group were compared with the normonatremia group and patients in the hypokalmic group were compared with normokalmy group, all of which were in regards to clinical outcomes. Results: There was a significant difference between the two groups of sodium in successful weaning (P<0. 05), but, there was no significant difference in endotracheal tube extubation, duration of hospital stay, duration of mechanical ventilation, and mortality rate (P>0. 05). There was also a significant difference between the two groups of potassium in successful weaning and mortality rate (P>0. 05); however, no significant difference was observed in the endotracheal tube extubation, duration of mechanical ventilation, and duration of hospital stay (P>0. 05). Conclusion: Serum levels of potassium and sodium affect the clinical outcome of head trauma patients.