Objective: To determine the prevalence of vitamin D deficiency among children in Riyadh City, and to investigate the relationship between vitamin D level and age and sex.

Methods: Conducted between January and November 2023, this cross-sectional study included 1000 children aged 2–14 years who were ordered for vitamin D level testing for different reasons. Data on age and sex were recorded, and vitamin D level was measured as serum 25(OH) vitamin D. Vitamin D levels were categorized into three groups: sufficiency (>50 nmol/mL), insufficiency (30–50 nmol/mL), and deficiency (<30 nmol/mL).

Results: Of 1000, 50.9% were boys and 12.6% showed vitamin D deficiency, 43.6% insufficiency, and 43.8% sufficiency. Children aged 2–8 years were less likely to be vitamin deficient compared to those aged > 8 years. Vitamin D deficiency was more prevalent in girls than in boys.