Objective · To explore the number of regulatory B cells in peripheral blood in patients with pemphigus and its significance in the incidence of pemphigus. Methods · Peripheral venous blood specimens were collected from 40 patients with pemphigus and 20 healthy controls. Flow cytometry was conducted to measure the number of CD19+IL-10+ B cells after stimulation for 5 and 48 h and the number of CD19+ B cells in peripheral blood. The serum anti-dsg1 antibody and anti-dsg3 antibody titers were measured with ELISA. Results · The difference in the proportion of CD19+ B cells in peripheral blood between pemphigus patients and healthy controls was not statistically significant (P>0.05). There was no significant difference in CD19+ B cells in pemphigus patients at acute onset, chronic active and remittent stages (P>0.05). The number of CD19+IL-10+B cells was significantly higher in pemphigus patients than in healthy controls 5 h after in vitro stimulation (P=0.008). However, the difference between two groups was not statistically significant 48 h after stimulation (P<0.05). In 20 PV patients, the anti-dsg3 antibody titers were significantly higher in patients at acute onset and chronic active stages than in patients at remittent stage (P>0.05). In 20 PF patients, the anti-dsg1 antibody titers were significantly higher in patients at acute onset and chronic active stages than patients in remittent stage (P<0.05). Conclusion · The pathogenic antibody titers in pemphigus patients are not associated with the number of B cells but are associated with disease activity. The function of regulatory B cells in peripheral blood in pemphigus patients may have defects.