Background: Vitamin D receptor (VDR) gene polymorphisms have been demonstrated in the development of autoimmune diseases. Also, vitamin D deficiency has been linked with the development of autoimmune diseases. Immune thrombocytopenia purpura (ITP) is developed secondary to the production of autoantibodies against platelets leading to isolated thrombocytopenia. Objective: This study aimed to evaluate the association between VDR gene polymorphism and susceptibility to ITP in children as well as other prognostic factors. Patients and Methods: A case-control study included 60 subjects and conducted at Hematology Unit of Pediatric Department and Clinical Pathology Department at Zagazig University Hospital. Children were divided into: case group included 30 children with primary ITP and the control group included 30 matched healthy children 15. All the included subjects were subjected to the following: history taking, physical examination, laboratory investigations. Results: There was no statistical significance difference between the studied groups regarding age or sex. Platelets count between the studied groups ranged from 6 to 38 x103/mm³ with mean 16.63±7.89 and median 17 x103/mm³. There was no statistical significant relation between VDR BsmI gene polymorphism and sex, frequency of upper respiratory tract infection (URTI), purpura and ecchymosis; but there was a statistical significant increase in frequency of wet bleeding among BB genotype compared to other genotypes. There was no relation between VDR BsmI analysis and line of treatment among the studied cases group. Conclusion: VDR BsmI polymorphism can be used as a risk marker for ITP susceptibility in children. There was an association of VDR BsmI genotype frequency in ITP patients with no effect on platelet count or bleeding severity.