Background and Aim: Glioblastoma multiform is one of the most common primary malignant brain tumors in adults. Recent studies have shown that micronutrients, such as selenium, have the potential to have positive effects in the treatment of glioblastoma and can be a promising candidate combined with surgical and radiochemical therapies. The aim of this study was to evaluate the anti-cancer effects of selenium on brain tumor damages. Methods: Rats were randomly divided into three main groups: control and selenium-received groups at doses of 0. 5 and 1. 5 mg/kg. A 1 × 106 rat Glioma C6 cells were transplanted in the right caudate nucleus of the rat brain. Five days after surgery, the treatment groups received selenium intraperitoneally for five days. Motor activity, animal weight, tumor volume, survival rate, and histopathological changes were assessed. Results: Selenium 0. 5 mg/kg reduced tumor volume, improved locomotor activity, and attenuated weight loss of the animals. Also, histological analysis showed a significant reduction in tumor volume and invasion of tumor cells to the surrounding tissues of tumor in rats treated by selenium 0. 5 mg/kg. Conclusion: According to the present results, it can be stated that selenium has sufficient potential to inhibit brain tumor damages.