Oxidative stress may play a role in the pathogenesis of immune thrombocytopenia (ITP), but the role of dynamic thiol/disulfide homeostasis has not been studied. The objective of this study was to assess whether there is a change in thiol/disulfide homeostasis in children with acute ITP. A total of 40 children with acute ITP and 50 healthy age-matched and sex-matched controls were included in this study. Serum total thiol and native thiol levels have been measured with a novel automatic spectrophotometric method. The amount of dynamic disulfide bonds and related ratios were calculated from these values. The average total thiol and native thiol levels of the patient group were found to be significantly lower than those levels of controls (P<0.01). However, intravenous immunoglobulin (IVIG) treatment with 1 g/kg/d prevented these reductions. disulfide level was slightly, but not significantly, depressed in ITP patients, but it recovered following IVIG treatment. We detected no marked changes in disulfide/total thiol, disulfide/native thiol, and native thiol/total thiol ratios between groups. These results are the first to demonstrate that thiol/disulfide homeostasis plays a role in ITP pathogenesis, and IVIG treatment can prevent the reduced thiol levels in children.