Introduction: Immune thrombocytopenia (ITP) is the commonest cause of pediatric 
thrombocytopenia. Vitamin D (VD) is multifunctional hormone that regulates multiple activities in 
human body especially in immune system. Aim of the work: to investigate the role of VD as an 
immune modulating drug in the treatment of ITP in children. Patients and Methods: This cohort 
study was carried out on 80 patients with ITP. Cases are taken and divided into: Group I: It includes 
40 children with acute ITP. They were subdivided into: Group I.A: 20 children will receive VD 
supplementation & Group I.B: 20 children will not receive VD. Group II: It includes 40 children with 
chronic ITP. They were subdivided into: Group II.A: 20 children will receive VD supplementation & 
Group II.B: 20 children will not receive VD. Results: VD level was low in all cases. VD 
supplementation improved platelets count. Discussion: VD deficiency may contribute to pathogenesis 
of ITP. VD supplementation was beneficial for acute and chronic ITP in children. Recommendation: 
Based on the current study we recommend VD assay in all cases of ITP to detect deficiency and give 
supplementation.