In the first part of the paper the Authors give an up-to-date analysis of our current knowledge of magnesium metabolism, its relation with other electrolytes (namely sodium, potassium, calcium) and clinical symptoms due to its deficiency. The Authors then focus their attention on the relations between magnesium and cardiovascular pathologies and underline the role which magnesium deficiency may play in the onset of various forms of coronary artery disease: preinfarction angina, myocardial infarction, threatening ventricular arrhythmia and sudden death.