The aim of the present study was to investigate the efficacy and side-effects of preventive treatment with pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) on concurrent chemoradiotherapy-induced grade IV neutropenia and to provide a rational basis for its clinical application. A total of 114 patients with concurrent chemoradiotherapy-induced grade IV neutropenia were enrolled. A randomized approach was used to divide the patients into an experimental group and a control group. The experimental group included three subgroups, namely a P-50 group, P-100 group and P + R group. The P-50 group had 42 cases, which were given a single 50-mu g/kg subcutaneous injection of PEG-rhG-CSF. The P-100 group had 30 cases, which received a single 100-mu g/kg subcutaneous injection of PEG-rhG-CSF. The P + R group comprised 22 cases, which were given a single 50-mu g/kg subcutaneous injection of PEG-rhG-CSF and rhG-CSF 5 mu g/kg/day; when the absolute neutrophil count (ANC) was >= 2.0x10(9)/l, the administration of rhG-CSF was stopped. The control group (RC group) comprised 20 patients, who received rhG-CSF 5 mu g/kg/day by subcutaneous injection until the ANC was >= 2.0x10(9)/l. Changes in the neutrophil proliferation rate and ANC values over time, the neutropenic symptom remission time and incidence of adverse drug reactions were analyzed statistically in each group of patients. In the experimental group, the neutrophil proliferation rate and ANC values were significantly higher than those in the control group; the clinical effects began 12-24 h after treatment in the experimental group, and indicated that the treatment improved neutropenia in similar to 48 h after treatment. There was no significant difference in the neutrophil proliferation rate and ANC values between the P-50 and P+R groups. In the experimental group, the remission time of neutropenia-induced fever and muscle pain after administration was significantly shorter than that in the control group, with a statistically significant difference (P<0.05). The adverse drug reaction rates showed no significant difference between the experimental group and the control group. PEG-rhG-CSF had good efficacy and safety in the treatment of concurrent chemotherapy-induced grade IV neutropenia. For the treatment of concurrent chemotherapy-induced grade IV neutropenia, a single subcutaneous injection of 50 mu g/kg PEG-rhG-CSF is the recommended dose. The effects begin at 12-24 h; if the ANC values are not significantly improved during this time, no supplementary administration of rhG-CSF is necessary.