The use of magnesium sulphate has recently increased in anesthesiology and pain medicine. The roles of magnesium sulphate are as an analgesic adjuvant, a vasodilator, a calcium channel blocker and reducing the anesthetic requirement. These effect are primarily based on the regulation of calcium influx into the cell and antagonism of the N-methyl-D-aspartate receptor. We discuss here the clinical effects of magnesium sulphate on anesthesiology and pain medicine.