Magnesium possesses numerous salutary effects for the treatment of acute myocardial infarction (AMI). It is a coronary vasodilator, calcium antagonist, afterload reducer, antiarrhythmic, and antiplatelet drug that modulates autonomic function and limits reperfusion injury when administered early in infarction. Various clinical trials of magnesium therapy for AMI have proffered conflicting results as to the efficacy of magnesium therapy because of significant differences in the timing of magnesium administration. Additional clinical trials that focus on early administration of magnesium are warranted to delineate the role of magnesium therapy for AMI.