Though pathogenesis of primary immune thrombocytopenia (ITP) is still rendered unclear, yet there are many research efforts that have been directed to the role of T helper 17 (Th17) and interleukin 17 (IL-17) in the pathogenesis of this disease. The Th17 cell, which produces IL-17, is a subset of T helper cells. Interleukin 17 is pro-inflammatory cytokine that is recently proved to have a crucial role in the emergence of autoimmune diseases. We aimed to investigate the role of T helper17 cells and interleukin-17 in the pathogenesis of ITP in Egyptian children. This study was carried out on 100 children with ITP and 100 apparently healthy children as a control group. Patients were subjected to full medical history taking, thorough physical examination and routine investigations according to our local standards. Percentage of Th17 cells was measured by flow cytometry in study groups. Also, serum IL-17 was measured in in study groups by ELISA. Th 17 cells were significantly higher in patients compared to controls. Moreover, 3.1-fold increased serum levels of IL-17 were observed in patients with ITP compared to controls. Newly diagnosed patients had significantly higher percentage of Th-17cells as well as higher IL-17 levels than patients with either persistent or chronic ITP. Conclusion: We concluded that Th 17 cells and IL-17 seem to play an important role in the pathogenesis of ITP in Egyptian children.