Background/aim: Mortality and morbidity still remain high in patients with traumatic brain injuries. Understanding the role of new treatments in these patients is critical. The aim of this study was to determine the effect of simvastatin on survival and outcome in traumatic brain injury patients. Materials and methods: Forty-four patients were assigned to receive either simvastatin or a placebo. The serum interleukin-6 and C-reactive protein levels were measured at the first 24 h and 48 h after trauma. All data, including the Glasgow Coma Scale score, survival at discharge, length of intensive care unit stay, and duration of mechanical ventilation, were collected. The effect of simvastatin on the collected data was then investigated. Results: The Glasgow Coma Scale level at discharge was significantly higher in the simvastatin group. The overall mortality rate, duration of mechanical ventilation, and length of intensive care unit stay were similar between the 2 groups. The C-reactive protein concentration 48 h after trauma was significantly lower in the simvastatin group, but there was no significant difference according to the interleukin-6 level 48 h after trauma between the 2 groups. Conclusion: Simvastatin could be suggested as an adjunctive therapy in traumatic brain injury patients.