Magnesium (Mg) plays an essential role in a wide range of fundamental cellular reactions in patients with ischemic heart disease. It has been well known that Mg plays a pivotal role in control of cardiac excitability, neuromuscular transmission, vasomotor tone, and blood pressure, among other functions. Especially, many epidemiological, experimental, and clinical studies support a pathological role for Mg in the etiology and development of major coronary risk factors as diabetes mellitus, hypertension, and hyperlipidemia as well as ischemic heart disease. Furthermore, the therapeutic value of Mg in the management of coronary risk factors and ischemic heart disease has been clarified. Dietary Mg supplementation should be considered as a preventive element in atherosclerosis and ischemic heart disease.