This study was aimed to investigate the role of regulatory B cells (Breg) in pathogenesis of immune thrombocytopenia (ITP) and its clinical significance. A total of 35 ITP patients and 20 normal controls were enrolled in this study. The expression of CD19(+)CD24(hi)CD38(hi) B cells was detected by flow cytometry and the expression of IL-10 mRNA and TGF-β1 mRNA was assayed by RT-PCR. The results indicated that the expression level of CD19(+)CD24(hi)CD38(hi) B cells in peripheral blood of newly diagnosed ITP patients was obviously lower than that in normal controls (P < 0.05); the expression level of CD19(+)CD24(hi)CD38(hi) B cells in ITP patients with increased platelet count after treatment was higher than that before treatment (P < 0.05); the expression level of IL-10 mRNA in newly diagnosed ITP patients was significantly lower than that the in normal controls (P < 0.05), the expression level of TGF-β1 mRNA in newly diagnosed ITP patients increases as compared with normal controls (P < 0.05), after treatment with DXM the expression of IL-10 mRNA was enhanced, the expression of TGF-β1 mRNA was reduced as compared with expression level before treatment (P < 0.05). It is concluded that the Breg cells may play an important role in the pathogenesis of ITP via humoral immunity and its regulation of T lymphocytes.