Epidemiological and experimental studies have shown that magnesium is closely related to regulation of lipid metabolism, membrane structure and permeability, ion migration through cellular membranes, ...endocrine hormone and platelet function. The cause of atherosclerosis induced by magnesium deficiency has been suggested to be due to abnormal lipid metabolism, lipid peroxidation, a decrease of prostacycline produced by endothelial cells, and an increase of platelet aggregation. We found that the plasma from cardiac catheterized patients suffering from chest pains contained higher levels of oxysterols than age and sex matched patients free of chest pain. Studies with cultured arterial cells in media deficient in magnesium or containing oxysterols indicated that both magnesium and oxysterols have an important role in lipid metabolism in patients with coronary heart disease.