Introduction: Pediatric patients with sickle cell disease and vitamin D deficiency have worse clinical and laboratory outcomes. This study aims to quantify the prevalence of vitamin D deficiency in this population and identify possible risk factors for hypovitaminosis D. Methods: A cross-sectional study with children aged three to eighteen years old with sickle cell disease. Patients were clustered into two groups regarding vitamin D deficiency (25-OH-D < 20 ng/mL). Results: 60 patients were evaluated, with a mean age of 10.80+4.21 years. The prevalence of vitamin D deficiency was 46.7% (21.02±8.47 ng/mL). When comparing groups with and without vitamin D deficiency, age (p=0.002) and season of 25-OH-D collection (p=0.005) were statistically significant. Age presented OR 1.23 (95%CI:1.07;1.41 / p=0.004), as well as the season of the 25-OH-D collection with OR 5.21 (95%CI:1.58;17.14 / p=0.007) for autumn/winter assessment. After linear regression, an association was noted for age (β = -0,80/ 95%CI:-1.29;-0.320/ p=0.002), days of sun exposure (β = 0.83/ 95%CI:0.07;1.58/ p=0.032), and autumn/winter vitamin D assessment (β = -7.94/ 95%CI:-12.02;-3.85/ p=0.032). Conclusion: Hypovitaminosis D is highly prevalent in this population; meanwhile, age, season of 25-OH-D collection, and days of sunlight exposure appeared as risk factors for deficiency.