Urinary tract infections (UTIs) are one of the most common bacterial infections in the global population. Vitamin D deficiency is also an urgent and common problem, and the high incidence of hypovitaminosis does not depend on age, sex, nationality, and geographical location. Along with the so-called "classical" effects of cholecalciferol, no less significant non-calcemic functions of cholecalciferol have been actively studied over the past two decades, particularly its effect on inflammation and its role in anti-infectious immunity. More and more data on the relationship between UTIs and vitamin D deficiency supports the possible use of cholecalciferol as an adjuvant to basic UTI therapy.
 Aim. To analyze the vitamin D status in children with UTI compared to healthy ones.
 Materials and methods. The study included 75 children from 1 month to 18 years with UTIs of various localization treated in a healthcare institution in Stavropol. The mean age of the study patients was 6.0±0.3 years. Vitamin D status was based on serum calcidiol [25(OH)D3] level.
 Results. The vitamin D level is statistically significantly higher in children of the control group than in patients with UTI: 36.42 ng/mL [24.92–46.37] vs 24.13 ng/mL [13.75–36.42], respectively (p=0.003). There were no patients with severe vitamin deficiency in the control group, while in the UTI group, it occurred in 20.0% of patients. The vitamin D level was less than 20 ng/mL in 31 (41.3%) children with UTI and only 2 (6.6%) in the control group (p=0.001). Normal vitamin status was found in only 38.7% of patients with UTI compared to 66.7% of healthy children (p0.01). The lowest level was found in patients with acute cystitis – 19.7 ng/mL [9.8–19.7], and the highest in patients with acute pyelonephritis – 31.9 ng/mL [14.3–36.4].
 Conclusion. Based on the study results, it can be concluded that vitamin D deficiency may be one of the risk factors for developing UTIs in children. Further studies involving more patients are needed.