The earliest description of clinical magnesium deficiency was reported in 1934. In 1954, Flink reported alcoholism as a cause of magnesium deficiency. This has been confirmed by low serum and tissue levels, balance studies, low exchangeable 28Mg and parenteral Mg retention tests. Alcohol causes urinary Mg wastage, but other mechanisms related to alcoholism contribute to the magnesium deficiency including malnutrition, gastrointestinal losses, phosphate deficiency, acidosis and/or alkalosis, vitamin D deficiency and free fatty acidemia associated with alcohol withdrawal. Mg replacement therapy is recommended to prevent some of the serious sequelae of magnesium deficiency.