Background: Research efforts have been directed to the role of different cytokines in the pathogenesis of primary immune thrombocytopenia (ITP) in children. Interleukin-10 (IL-10) is anti-inflammatory cytokine which may play a role in the pathogenesis of this disease and prediction of its chronicity. Objectives: We aimed to determine the serum level of interleukin 10 in children with ITP and to evaluate its relationship with disease chronicity and other clinical and laboratory variables in these patients. Patients and Methods: This study was carried out on 100 children with ITP and 100 age- and sex-matched healthy children as a control group. Patients were subjected to full history taking, thorough clinical examination and routine investigations according to our local standards. Serum IL-10 was measured in patients and controls by ELISA method. Results: Patients had significantly higher levels of serum IL-10 than controls. Newly diagnosed patients had significantly higher levels than patients with persistent and chronic ITP. There was a significant negative correlation between serum IL-10 levels and age of patients. Females had significantly higher IL-10 levels than males. Conclusion: We concluded that serum IL-10 seems to predict susceptibility to primary immune thrombocytopenia in Egyptian children.