Homeostasis of magnesium in the body is a prerequisite for human health. As required macrocell for cells and tissues, magnesium is involved in many physiological processes, to ensure the normal functioning of the organism. At the same time a number of large-scale studies established a significant prevalence of magnesium deficiency, which is in the general population is 14.5%, and the suboptimal level observed in 33.7%. The resolution of the International Advisory Council for magnesium deficiency in obstetrics and gynecology noted urgency of the problem and the importance of correction of magnesium deficiency in pregnant and gynecological patients. The lecture covered various aspects of magnesium deficiency are considered violations of the pathophysiological mechanisms of magnesium homeostasis, Principles on the Use of magnesium products with preventive and curative purposes. Key words: magnesium deficiency, clinical symptoms of hypomagnesemia, pregnancy.