Many factors can ultimately lead to an increased blood pressure and it is a generally accepted view that an increase in the active tension of arterioles reflects an increase of the free calcium concentration in the cytosol of the vascular smooth muscle cells. Only recently, however, has the possibility been considered that blood pressure regulation could be influenced by calcium homeostasis. A background for these studies has been provided by the epidemiological observations which link hypertension to a low dietary intake of calcium as well as experimental studies in animals, mostly rats, which have demonstrated that various disturbances of calcium metabolism are related to a raised blood pressure. This review is focused on clinical studies of a possible association between systemic calcium metabolism and the regulation of blood pressure.