Background:Vitamin D is a pleiotropic hormone essential for optimal health. Critical illness in children is a major cause of significant health-care utilization and mortality around the world. The association of Vitamin D deficiency (VDD) in critically ill adults has been well-studied, in comparison, the importance of Vitamin D in pediatric critical illness has been much less studied.Aim and Objectives:This study aimed to assess Vitamin D status and its determinants in patients admitted to a pediatric intensive care unit (PICU) in North of Turkey. We also investigated the association between Vitamin D status and clinical outcomes.Materials and Methods:All patients aged 1 month to 18 years admitted to the PICU of a tertiary care hospital who had levels of 25-hydroxy Vitamin D available within 24 h of admission were included in this retrospective study. VDD was defined as <20 ng/mL levels.Results:VDD was observed in 120 (58.5*) children. In multivariable linear regression model, only identified patient age and winter season as statistically associated with VDD. Vitamin D deficient patients were older and heavier and were more likely to receive catecholamine. There was no association between Vitamin D deficiency and other illness severity factors including mortality.Conclusions:Hypovitaminosis D occurrence was high in critically ill children and was associated with higher vasopressor requirement but not with other markers of illness severity including mortality.