Results of the numerous researches conducted from the moment of vitamin D (VD) discovery emphasize its key role in a regulation of calcium and phosphorus exchange, providing a bone tissue healthy metabolism. It is necessary to emphasize that the biological role of VD is not limited only to a bone metabolism regulation. The two last decade’s scientific researches significantly expanded our ideas of VD role in a human body. Research of VD extraskeletal effects allowed to find its ability to influence at gene and molecular level on synthesis of a numerous factors, that participate in various cells proliferation, differentiation and in their apoptosis regulation. Violation of a vitamin-dependent expression regulation of the above factors increases probability of different localization malignant growth. The by now cumulated dates testify to VD important effects on cardiovascular system functioning. It is proved that low 25(OH)D concentration is independent risk factor of development of such cardiovascular violations as coronary heart disease, myocardial infarction, heart failure, stroke, hypertension. Numerous researches confirm also a vitamin D role in pathogenesis of diabetes mellitus and development of metabolic syndrome including hypertension, obesity, insulin resistance and glucose tolerance. For last 3 decades the huge number of the facts confirming VD importance for the immune response is saved up. Confirmation of VD significance in immune regulation are data on correlation between VD low levels and the raised susceptibility to various infections, and also autoimmune and allergic pathology development. Thus, the condition of deficiency or a failure of VD gains the predictor importance of a wide range of pathological states development, and also promotes increase in indexes both of total mortality and lethality from cardiovascular pathology, oncopathology and respiratory organs diseases.