Objective: To study the effect of recombinated human granulocyte Colony-stimulating factor(rhG-CSF,Topneuter) on leukopenia caused by chemotherapy.Methods:Thirty cases with leukopenia caused by chemotherapy for patients with lung cancer were treated with rhG-CSF,and compared with 30 cases treated with oral leukopenic medicines.Results:All patients with leukopenia recovered to nomal after treatment either with rhG-CSF or with oral leukopenic medicines,the period of leukopenia recovered to normal was shorter in the group with rhG-CSF treatment than that in the leukopenic drugs group(P0 002) A significant decrease was also shown for rhG-CSF group in the incidence of infection(P=0 03).Conclusion:Topeneuter was effective for the treatment of leukopenia after chemotherapy,and it may decrease infection incidence during chemotherapy.