Objective To measure the number of peripheral blood CD34+ hematopoietic stem/progenitor cells (HSC/HPCs) and membrane expression of CD34 on these cells in patients with SLE. Methods Lymphocytes were isolated from peripheral blood of 30 patients with SLE and 14 normal human controls. Flow cytometry using FITC-labeled antibodies was performed to determine the percentage of CD34+ HSC/HPCs and mean fluorescence intensity (MFI) of CD34 on these cells. Their correlation with clinical data was analyzed.Results The percentage of CD34+ HSC/HPCs in peripheral lymphocytes was (0.15 ± 0.10)% and (0.09 ±0.07)% in active and stable SLE patients, respectively, significantly lower than that in normal controls [(0.37 +0.17)%, F = 17.18, P ＜ 0.01], however, there was no significant difference between active and stable SLE patients (t = 1.51, P＞ 0.05). The MFI of CD34 was higher in active SLE patients than in the normal controls (41.35 ± 19.24 vs. 27.43 ± 7.57, F= 3.13, P ＜ 0.05), but no difference was observed between stable SLE patients and normal controls (F= 3.13, P ＞ 0.05). In patients with SLE, the percentage of CD34+ HSC/HPCs was negatively correlated with serum IgG levels (r = -0.588, P ＜ 0.01 ), but uncorrelated with SLE disease activity index (SLEDAI) or serum levels of complement, anti-dsDNA antibodies, anti-C1q antibodies, antinucleosome antibodies, etc. Conclusions The count of CD34+ HSC/HPCs is reduced while the MFI of CD34 antigen is elevated in SLE patients, hinting that there is a functional abnormality of HSC/HPCs in SLE patients, which may be involved in the pathogenesis of SLE.