 Magnesium sulfate MgSO4 has anti-shivering effects. Moreover, it has potential neuroprotective effects and may enhance neuroprotection against the effects of hypothermia. Intrathecal MgSO4 administration provides effective perioperative analgesia and can prolong the period of anesthesia and sensory blockade without any additional side-effects. However, most of the research on the role of MgSO4 in the prevention of shivering has focused on intravenous infusion of this drug. Few clinical trials have examined the effect of adding intrathecal MgSO4 to anesthetic agents such as bupivacaine to suppress anesthesia-related shivering in patients. Similar to infusion studies, we hypothesized that the addition of intrathecal injection of MgSO4 to bupivacaine would improve perioperative shivering in female patients undergoing elective caesarean section. Few previous studies evaluated neuroaxial anti-shivering effects of intrathecal magnesium and none evaluated the anti-shivering effect of intrathecal MgSO4. Therefore, we elected to use the lowest dosage 25 mg MgSO4 that was formerly utilized for investigation of analgesic effects. 