Abstract: [Abstract] Immune thrombocytopenia (ITP), the most common hemorrhagic disease, is an organ-specific autoimmune disease characterized by decreased platelets count due to auto- antibodies mediating platelets destruction and insufficient platelets production. The etiology of ITP is still not completely known. Regulatory T cells, also called Tregs, are character? ized by CD4 + CD25 + , and positive of transcription factor forkhead box P3. They belong to a subpopulation of T cells special? ized for immune regulation and play an important role in maintaining the immune balance. Decreased production and defect? ed function of CD4 + CD25 + Treg was found not only in the ITP animal model but also in the ITP patients. It indicates that the Treg was involved in the pathology of ITP. This review focus on the characteristic and function of Tregs and their relationship with pathogenesis of ITP.