Vitamin D affects both innate and adaptive immune responses, which have been held responsible in immune thrombocytopenia (ITP) pathogenesis. This study aimed to assess the role of Vitamin D and VDR polymorphism on the pathogenesis of newly diagnosed children with immune thrombocytopenic Purpura. Methods: a case control study was conducted at Hematology and Oncology Unit, Pediatric Department, Zagazig University Hospital on 42 newly diagnosed children with ITP and 42 age and sex-matched healthy children as control group during a period between October2017 until November 2018. All the studied groups subjected to full history taking , thorough clinical examination and laboratory investigation in the form of complete blood count, Bone marrow aspiration (when indicated), serum calcium, serum phosphorus and alkaline phosphatase , serum 25 ( OH) D3 and vit D Cdx-2 (rs11568820)) gene polymorphism was determined using Tetra Amplification refractory mutation system - polymerase chain reaction (T-ARMS-PCR) . Results: vitamin D level of ITP patient was (27.24±14.11 ng/ml) and of the control group (24.24±13.23 ng/ml) with no significant difference between both. There was no significant difference between ITP group and controls regarding allele and genotype distributions of vit D Cdx-2 (rs11568820) (OR 0.92 , 95 % CI 0.42-2.01 and p=0. 842 for A allele). Conclusion: Vitamin D receptor polymorphism Cdx-2 (rs11568820) does not play a role in the pathogenesis of ITP in this study