Adequate intake of vitamin D and its concentration in serum is important for the health of bones and calcium-phosphorus metabolism and for the optimal functioning of many organs and tissues. Most epidemiological studies have shown that vitamin D deficiency is widespread among the population in Russian Federation. Material and methods. We reviewed relevant literature on the epidemiology of insufficiency and deficiency, skeletal and extraskeletal effects of vitamin D and summarized recommendations for the diagnosis, prevention and treatment of vitamin D deficiency in the general population, which were subsequently discussed and amended in conjunction with leading endocrinologists of the Russian Federation who are experts in this subject. Results. The optimal concentration of 25(OH)D in the serum as the best indicator of vitamin D body stores is recognized as 30-100 ng/ml (75-250 nmol/l), insufficiency - from 20 to 30 ng/ml (50 to 75 nmol/l), deficiency - less than 20 ng/ml (less than 50 nmol/l). In prevention and treatment it is recommended to stick to the target serum levels of 25(OH)D in the range of 30-60 ng/ml (75-150 nmol/l). We’ve developed a general practice recommendations for the prevention, diagnosis and treatment of vitamin D deficiency in adults, including pregnant and lactating women, persons over 50 years old and subjects suffering from various diseases affecting the metabolism of vitamin D. Conclusions. Increased sufficiency of vitamin D in the population should be included as one of the priorities of modern healthcare due to proven preventive health effects on the musculoskeletal system and the potential positive impact on many socially significant diseases. This publication is a detailed version of the Federal Guideline.