Introduction: Themaintenance of hemodynamic stability in brain aneurysm surgery has paramount clinical significance in order to prevent vasospasm in the patients with aneurysmal subarachnoid hemorrhage. Regarding this, the present study was conducted to assess the role of magnesium sulfate in preventing vasospasm and maintaining hemodynamic stability during endovascular coiling procedure for brain aneurysm. Materials and Methods: This double-blind clinical trial was conducted on 60 patients who were candidates for undergoing endovascular coiling for brain aneurysm. The patients were subjected to angiography through femoral artery catheterization. Then, they were randomly assigned into two treatment groups of case receiving magnesium sulfate and control administered normal saline. The vasospasm and hemodynamic status were measured and recorded during and following the surgery. Results: According to the results, no significant difference was observed between the two groups in terms of heart rate (p=0.98) and mean arterial pressure =p) 0.89( one hour post-surgery. Furthermore, there was no statistical difference between the two groups regarding the use of nimodipine ( p=0.11). Nevertheless, the frequency of vasospasm was significantly lower in the patients receiving magnesium sulfate, during surgery (p=0.037) and after surgery (p=0.02), compared to those administered normal saline. Conclusion: As the findings indicated, magnesium sulfate could lower the incidence of vasospasm during and following the endovascular coiling procedure for brain aneurysm. Moreover, it resulted in no adverse effects on the hemodynamic status of the patients.