Background. The world's population has been undergoing significant structural changes over the past fifty years due to an increase in life expectancy. Centenarians represent an optimal model of physiological aging, reflecting the timeliness of the body's adaptive reactions to changing factors of the internal and external environment. The dominant role in maintaining the autonomy of an older patient is assigned to the functional status. Aim: to study the features of the functional status of centenarians of the Samara region in relation to the concentration of 25-hydroxyvitamin D (25(OH) D, 25-Hydroxycalciferol) in blood serum. Materials and methods. Our work is based on the analysis of the survey results of 62 centenarians aged 90 to 101 years, the average age is 92.29 ± 2.40 years. To assess the level of functional activity and the need for outside help, a standard scale for assessing basic functional activity (Barthel Index) was used. The study of vitamin D status was performed on an automatic chemiluminescent immunoanalyzer by the method of chemiluminescent immunoanalysis on microparticles. To exclude secondary hyperparathyroidism, blood samples were taken from all participants and plasma parathyroid hormone levels were measured by enzyme-linked immunosorbent assay. To assess the effect of vitamin D levels on the formation of dependence, a one-dimensional logistic regression analysis was performed. Results. The study showed that functional dependence is common among centenarians in 82.3% of cases. Decrease in vitamin D levels below thresholds values in the general sample was 88.7%, among men – in 91.3% of cases, among women – in 87.17%. In patients with functional dependence, higher levels of parathyroid hormone in blood plasma were detected 51.3 ± 6.3 pg/ml compared with patients who retained autonomy, 46.4 ± 5.2 pg/ml, which had a significant difference (p=0.034), however, did not go beyond the reference values. As a result of our study, we found that the functional status of centenarians significantly depends on the level of PTH and serum vitamin D. The risk of addiction increases proportionally to the decrease in serum vitamin D levels – at vitamin D levels ≤ 10 ng/ml, the risk is significant. Conclusions. Maintaining adequate vitamin D levels or taking vitamin D supplements among centenarians can potentially help prevent the formation of addiction and preserve the autonomy of our patients.