Abstract. One of the vital minerals in the human body is calcium. This mineral takes part in more than 300 biologically active reactions. Medicines containing calcium salts have been used in medicine for many decades. This is due to the important role of this element in the modeling, remodeling and mineralization of bones. Depending on body type and gender, about 97-98% of calcium is found in the skeleton, in the form of hydroxypatite, and only 2-3% in other tissues (muscles, skin). In total, the adult human body contains about 1000-1500 mg of Ca. In the body, calcium is found in two forms - ionized (free) and bound to Ca proteins (mainly albumins). A decrease in the concentration of ionized calcium causes signs of hypocalcemia. Calcium ions perform the following functions: activates the plastic function of osteoblasts and osteocytes; participate in the formation of bone and dental tissues; form the mineral basis of the skeleton, ensuring their strength and hardness; By interacting with the intracellular protein calmodulin, calcium ions regulate many biochemical processes. Calcium also plays a key role in a number of functions of the human body, including: cell division and differentiation; in the release of the transmitter from the endings of the efferent nerves into the synaptic cleft and the conduction of nerve impulses; in contraction – relaxation (together with troponin) of striated and smooth muscles; in the activity of neurosecretory organs; in the process of blood clotting; in transmembrane ion reactions involving selective calcium channels; in the regulation of the permeability of cell membranes and the activity of many enzymes and other protein, as well as non-protein, btologically active substances.