Although the complexities of cardiovascular physiology preclude any one factor from assuming the role of the key determinant of elevated blood pressure, the large body of evidence that is accumulating based on epidemiologic observation and studies in experimental and human hypertension support the contention that maintenance of normal calcium metabolism is associated with a lower arterial pressure. Dietary calcium supplementation in human essential hypertension appears to be an effective nonpharmacologic means of lowering blood pressure in some patients, especially those with evidence of a calcium-deficient state. In addition, preliminary evidence has raised questions as to whether a relationship exists between salt sensitivity and disordered calcium homeostasis in some hypertensive patients, and whether there is an important role for calcium in the regulation of other hormonal systems involved in blood pressure regulation.