Intravenous administration of magnesium has proved to have beneficial effect in acute myocardial infarction. Magnesium seems to act at different levels of the cardiovascular system. Of the greatest importance is the direct influence of Mg2+ on the cardiomyocyte which includes: reduction of cytoplasmatic calcium overload, protection of mitochondria against calcium influx, and diminution of cellular potassium, magnesium and ATP depletion. By means of these effects, or by its direct action on myocardium, Mg2+ inhibits the origin of postinfarctional dysrhythmias. Furthermore, magnesium reduces afterload by decrease in vascular resistance, and improves coronary flow. The mechanism underlying the protective effect of magnesium remains complex and poorly understood. Nevertheless, Mg2+ therapy is effective, undemanding, and easy to procure. Expectably, intravenous administration of Mg2+ may become a routine part of myocardial protection in acute myocardial infarction.