Magnesium (Mg 2? ) is the 2nd most abundant intracellular cation, which participates in various enzymatic reactions; there by regulating vital biological functions. Magnesium (Mg 2? ) can regulate several cations, including sodium, potassium, and calcium; it consequently maintains physiological functions like impulse conduction, blood pressure, heart rhythm, and muscle contraction. But, it doesn't get much attention in account with its functions, making it a ''Forgotten cation''. Like other cations, maintenance of the normal physiological level of Mg 2? is important. Its deficiency is associated with various diseases, which point out to the importance of Mg 2? as a drug. The roles of Mg 2? such as natural calcium antagonist, glutamate NMDA receptor blocker, vasodilator, antioxidant and anti-inflammatory agent are responsible for its therapeutic benefits. Various salts of Mg 2? are currently in clinical use, but their application is limited. This review collates all the possible mechanisms behind the behavior of magnesium as a drug at different disease conditions with clinical shreds of evidence. Keywords Magnesium Á Calcium antagonist Á Hypomagnesemia Á NMDA blocker Á Forgotten cation Á Vasodilator Abbreviations ACE Angiotensin converting enzyme AD Alzheimer's disease (AD) ALP Alkaline phosphatase ALT Aminotransferase AMPA a-Amino-3-hydroxy-5-methyl-4isoxazolepropionic acid APP Amyloid precursor protein AST Aspartate aminotransferase ATP Adenosine triphosphate BBB Blood brain barrier BMD Bone mineral density BMP2 Bone morphogenetic protein 2 BP Blood pressure cAMP Cyclic Adenosine mono phosphate CAD Coronary arytery diseases CFTR Cystic fibrosis transmembrane conductance regulator CGRP Calcitonin gene related peptide CHF Congestive heart Failure Claudin CLDN CNS Central nervous system CSD Cortical spreading depression CSF Cerebrospinal fluid CTF b C terminal fragment b CVD Cardiovascular diseases