Background: We conducted a meta-analysis to investigate the possible effects of vitamin D deficiency on clinical outcomes of critically-ill children.Methods: We searched Scopus-Embase and PubMed-Medline databases to find eligible observational articles. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the strength of associations.Results: Seventeen articles (eighteen studies) involving 2987 critically ill patients met our inclusion criteria. Vitamin D deficiency was not associated with increased mortality. A significant association was only observed in very high developed countries between vitamin D deficiency and risk of sepsis [OR (95%CIs): 2.65 (1.30, 5.41)] and ventilation support requirement [OR (95%CIs): 1.35 (1.03, 1.77)].Conclusion: Our findings suggest that vitamin D deficiency is not associated with higher mortality among critically ill children but increases susceptibility to sepsis and the need for ventilator support in critical care settings.