Immune thrombocytopenia (ITP) is an autoimmune disease characterized by peripheral thrombocyte destruction. In some autoimmune disorders, heat-shock proteins (HSP) are suggested to be an important antigenic factor. In this study, we demonstrated the serum free levels of HSP60, HSP70, anti-HSP60, and anti-HSP70 in ITP patients and healthy controls. Twenty-eight newly diagnosed ITP patients, 35 ITP patients in chronic phase, and 25 healthy controls were enrolled to this study. Serum levels of HSP60, HSP70, anti-HSP60, and anti-HSP70 were determined by the ELISA method. Serum HSP60 levels of newly diagnosed ITP patients were significantly decreased when compared with both chronic phase ITP patients and healthy controls. HSP60 levels of ITP patients (both newly diagnosed and chronic phase) with thrombocyte counts more than 30 x 10(9)/L were significantly increased compared with ITP patients with thrombocyte counts less than 30 x 10(9)/L and there was a positive correlation between thrombocyte counts and serum free HSP60 levels in ITP patients. This is the first study demonstrating the extracellular HSP levels in adult ITP patients. HSPs are shown to have a place in the pathogenesis of many autoimmune disorders. Low level of HSP60 may lead to lack of anti-inflammatory response due to less Treg activation, hence, could be a counterpart in the pathogenesis of ITP. Further studies are needed to understand the role of HSPs in the pathogenesis of ITP and whether they can be used for diagnosis, prognosis, and treatment of ITP.