Background: Immune thrombocytopenia (ITP) is an autoimmune disease characterized by isolated thrombocytopenia and increase risk of bleeding. The initial event leading to anti-platelet autoimmunity remains unclear. Objective: The aim of this study was to assess the role of T-regulatory cells in chronic ITP. Patients and methods: This cohort study was carried on 34 children with chronic immune thrombocytopenia who presented to the Pediatric Hematology Unit and Outpatient Clinic of Zagazig University Hospitals during the period from June 2020 up to march 2021 to assess the role of T-regulatory cells in children with chronic immune thrombocytopenia. Results: ITP patients were 20 females (58.8%), while 14 were males (41.2%). Consanguinity was reported in 6 patient (17.6%) while similar condition was found only in one patient (2.9 %). Patients were presented initially with purpura (44%) and ecchymosis (73.5%) while hematuria was detected in 5.9% and epistaxis in 38.2%. After six months significant improvement was detected in purpura (17.6%), ecchymosis (47%) and epistaxis (17.6%). The T regulatory cells were significantly increased after six months of follow up and there was significant positive correlation between platelet count and T regulatory cell level after six month of therapy. Conclusion: T- regulatory cells may play role in pathogenesis of chronic immune thrombocytopenia. Thus, T regulatory cells may play a role in modifying immune responses in these patients, resulting in new strategies of treatment and monitoring of disease activity.