Objective: To assess prevalence of 25 (OH) D deficiency in pediatricintensive care unit (PICU), possible risk factors and whether it isassociated with increased mortality and hospital stay.Subjects and Methods: Cross sectional study of 25(OH) D levelsmeasured in 88 patients during the 24 hours after critical care admission.Analysis of the demographic data and PRISM III score between thedeficient and sufficient group in the PICU. Vitamin D deficiency wasdefined as levels from 30 to 75 nmol/L and serious deficiency< 30nmol/L.Results: Median 25(OH)D level was 59.3 nmol/L in the whole studygroup of PICU patients. The prevalence of 25(OH)D < 30 nmol/L was34.1%. Patients with vitamin D deficiency had higher age and lowerplatelet count on admission to the PICU. Median age in severely deficientpatients was 3years with p value (0.046) and median platelet count waslower in severely deficient patients, it was 235 with p value (0.029).PRISM III score, mortality and duration of hospital stay were notassociated with vitamin D deficiency although PELOD score wasassociated with vitamin D deficiency.Conclusions: Hypovitaminosis D incidence was high in PICU patientsespecially those with older age, no vitamin D supplementation or sunexposure. Hypovitaminosis D was not associated with higher PRISM III scores or mortality.