The authors have studied the efficacy and safety of recombinant human granulocyte colony-stimulating factor (rhG-CSF, Granulocyte Injection) on leucopenia and neutropenia induced by chemotherapy with regimen CE (Carboplatin and Etoposide) in lung cancer patients in a randomized, matched and cross-over clinical trial. The total enrolled patients were twenty-two. They were randomized into A and B groups (11 patients in each group). Each patient received two cycles treatment. In group A chemotherapy and rhG-CSF were used in the first cycle and chemotherapy alone was used in the second cycle, while in group B chemotherapy alone was used in the first cycle and chemotherapy and rhG-CSF were used in the second cycle. The results showed that rhG-CSF significantly increased the number of white blood cell (WBC) and absolute neutrophil count (ANC) at the nadir, decreased incidence of leucopenia and neutropenia, and reduced the number of days with WBC < 4.0 x 10(9)/L, ANC < 2.5 x 10(9)/L as well as the number of days with WBC > 4.0 x 10(9)/L and ANC > 2.5 x 10(9)/L. rhG-CSF ensures the completion of chemotherapy and its side-effects were slight.