Abstract: Objective: To assess prevalence of 25 (OH)D deficiency in critically ill children , possible risk factors and whether it is associated with increased mortality and hospital stay Patients and Methods: This is cross sectional study of 25(OH) D levels conducted on 48 patients within the first 24 hours of PICU admission. Analysis of the demographic data and PRISM III score between the deficient and sufficient group in the PICU. Vitamin D deficiency was defined as levels from 30 to 75 nmol/L and serious deficiency< 30 nmol/L. Results: Median of 25(OH)D level was 63.7 nmol/L in the whole study group of PICU patients. The prevalence of 25(OH)D < 30 nmol/L was 33.3%, patients with vitamin D deficiency had higher age. Median age in severely deficient patients was 2.25 years with p value (