Traumatic brain injury is a common cause of death after trauma. The aim of this study was to investigate the relationship between oxidative stress parameters and, outcomes and clinical findings in patients with isolated traumatic brain injuries. Fifty-four patients who were admitted into the emergency department of Ankara Ataturk Training and Research hospital with isolated blunt traumatic brain injuries and 33 healthy adults as control group, were included in this study. Serum oxidant status was evaluated by measuring Total Oxidant Status (TOS) levels in patients with traumatic brain injury and in healthy individuals. Serum antioxidant status was evaluated by measuring Total Antioxidant Status (TAS) levels. Then, also Oxidative Stress Index (OSI) was calculated. A total of 54 patients with isolated traumatic brain injuries (mean age 36.7 +/- 18.3 years; 60.4% male, 39.6% female) were enrolled. TOS and OSI levels increased in patient group compared to the control group. High levels of OSI, TOS and TAS were observed in patients who finally became dead. A significant correlation between symptoms including nausea, vomitus, loss of consciousness, seizing and TOS, OSI levels of all patients have been observed. Moreover, there was a meaningful correlation between Glaskow Coma Scale (GCS) score, TOS and OSI levels of patients. The oxidative stress parameters may be valuable prognostic markers in traumatic brain injury patients. It can be concluded that oxidative stress parameters may be valuable in the assessment of clinical severity and in predicting outcome of traumatic brain injury patients.