Essential hypertension (EHT) is one of the most common risk factors for cerebrovascular and cardiovascular disease (CVD), which in turn are among the most common causes of death and disability in developed countries. Drug treatment of EHT has proven effective in lessening the risk of CVD, but has attendant risk of side effects, some of which are of risk to the CV system. Thus, increasing attention is being paid to non-drug treatment of EHT, which includes changing the daily intake of such electrolytes as sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg). Decreasing Na intake to control blood pressure (BP) is well established. On the basis of epidemiologic and experimental studies, increasing K and/or Mg intakes, and increasing of decreasing Ca intakes, have each been proposed to have beneficial effects of BP. Presented here is a review of the background data supporting the rationale for adding Mg to the anti-hypertensive regimen. There is evidence that Mg can exert a favorable effect in EHT, particularly when used in combination with K during diuretic therapy.