Treatments for brain edema are important and one of the major options is corticosteroids. Cell membrane stabilization and prevention of formation of free radicals are the main mechanisms of action of steroids in edema treatment. As an alternative therapeutic agent, magnesium sulphate has been used for its neuroprotective effect in various injury models. In our animal model of brain injury, cold has been used in Sprague-Dawley rats. After brain injury, magnesium sulphate (600 mg/kg) or dexamethasone sodium phosphate (0.2 mg/kg) were administered to experimental groups. The degree of brain edema and lipid peroxidation was evaluated using the wet-dry weight method, the determination of malondialdehyde (MDA) levels and an ultrastructural grading system. Magnesium sulphate treatment was found to be the most effective choice due to the absence of side effects and comparable efficacy to corticosteroids. (C) 2007 Elsevier Ltd. All rights reserved.