Pemphigus vulgaris (PV) is a potentially life-threatening autoimmune bullous disease affecting the skin and mucous membranes, whose pathogenic mechanism is still not fully understood. Regulatory T cells (Tregs) have been reported to play a significant role in regulating immune homeostasis in autoimmune disorders, such as PV.To investigate the potential role of Tregs in the immunopathogenesis of PV.Fifteen patients with PV and 15 healthy individuals were chosen for this work. Peripheral blood samples were collected from all participants before treatment. This was followed by flow cytometric, real-time RT-PCR, and in vitro inhibition based functional assays to explore the immunopathogenesis of Tregs in PV.Our results showed no statistically significant differences in total CD4+ CD25+ cells and CD4+ CD25high cells. In addition, expression levels of FOXP3 mRNA and the corresponding FOXP3 protein remained unchanged in normal controls and PV patients. However, the in vitro suppressive activity of CD4+ CD25+ T cell was impaired in PV patients compared to normal controls.Our observations suggest that inhibition of suppressive activity of Treg cells may be involved in the pathogenesis of PV.