Abstract： Objective To detect peripheral blood level of CD4+ CD25high CD127low regulatory T (Treg) cells in patients with B cell non-Hodgkin lymphoma (B-NHL) and to explore its clinical significance.Methods The levels of peripheral blood CD4+ CD25high CD127low Treg cells of 100 newly diagnosed patients with B-NHL and 50 healthy adults were detected and analyzed by flow cytometry.Results The levels of peripheral blood CD4+ CD25high CD12low Treg cells were 5.00 ％ and 7.20 ％ in healthy adults and newly diagnosed B-NHL patients,respectively.The difference was statistically significant (P ＜ 0.001).The level of peripheral blood CD4+ CD25high CD127low Treg cells was significantly higher in the male patients than that in the female (P ＜ 0.01).The level of peripheral blood CD4+ CD25high CD127low Treg cells was significantly higher in elevated LDH patients than that in normal LDH patients (P ＜ 0.01).The level of peripheral blood CD4+ CD25high CD127low Treg cells in stage Ⅲ-Ⅳ patients was significantly higher than that in stage Ⅰ-Ⅱ patients (P ＜ 0.01).The level of peripheral blood CD4+ CD25high CD127low Treg cells in B symptom patients was significantly higher than that in no B symptom patients (P ＜ 0.01).There was no significant relationship between the level of peripheral blood Treg cells and age,IPI score,bulky disease or pathologic subtype (all P ＞ 0.05).Conclusions B-NHL patients were in an immunosuppresive statue.Male,elevated LDH level,B symptom and Ⅲ-Ⅳ stage were correlated with higher level of peripheral blood CD4+ CD25high CD127low Treg cells.Level of peripheral blood Treg cells may be a useful prognostic factor for B-NHL.