Objective To evaluate the feasibility and safety of peripheral CD34+ cell mobilization in patients with severe autoimmune disease. Methods Forty-two patients underwent a total of 46 mobilizations by the regimen of cyclophosphamide 2-3 g/m2 +recombinant human granulocyte colony stimulating factor （rhG-CSF） 5 μg·kg-1·d-1. The positive selection of CD34+ cell was performed through the CliniMACS. Results In 8.1±2.3 days after administration of cyclophosphamide

the peripheral white blood cell and mononuclear cell （MNC） decreased to the lowest level. In 3.7±1.6 days after injection of rhG-CSF

the peripheral absolute MNC and CD34+ cell counts were 0.95×109/L and 0.035×109/L

respectively. After 2.4±0.6 times of leukapheresis

there gained 4.46×108/kg of MNC and 5.26×106/kg of CD34+

respectively. After mobilization

the underlying diseases were ameliorated more or less. In systemic lupus erythematosus （SLE） patients

SLE Disease Activity Index （SLEDAI） decreased from a median of 17 to 3 （P<0.01）. In rheumatic arthritis patients

an American College of Rheumatology criteria for 20%（ACR20） response was achieved in all five patients. Totally

17.4% of patients whose absolute neutrophil count <0.5×109/L suffered infection

and 31.0% of patients had bone pain after the injection of rhG-CSF. Two patients suffered severe complications

one with acute renal failure and recovered by hemodialysis

the other died of thrombotic thrombocytopenic purpura. Failed mobilization occurred in three patients. Conclusions Sufficient CD34+ cells can be mobilized by low dose of cyclophosphamide and rhG-CSF. CD34+ cell mobilization for treatment of severe autoimmune disease not only is appropriate in both effectiveness and safety but ameliorates disease also.