Abstract: Objective:To compare the efficacy of a single injection of pegylated filgrastim with daily doses of filgrastim as pro -phylaxis for chemotherapy-induced neutropenia in Chinese cancer patients. Methods:Single-institution data from a phase 2 study and a phase 3 trial on pegylated filgrastim were combined to analyze the efficacy and safety parameters. In the two randomized crossover tri-als, patients with previously untreated cancers received two cycles of chemotherapy with identical regimen. In the study cycle, the pa -tients received a single subcutaneous injection of pegylated filgrastim ( 100 μ g/kg), whereas those in the control cycle received daily subcutaneous injections of filgrastim ( 5 μ g/kg). Results:Among the 56patients enrolled, 53were evaluable for efficacy. These patients received one cycle with pegylated filgrastim prophylaxis and one cycle with filgrastim support each. Results indicated that 94.3% (50/53) of the cycles with pegylated filgrastim or filgrastim support did not develop grade 4 neutropenia. Moreover, febrile neutropenia did not occur in the cycles. The incidence rates of antibiotic administration were 7.5% (4/53) and 3.8% (2/53) in the pegylated filgrastim and filgrastim cycles, respectively (P=0.678). The median duration of filgrastim administration was 10days (3- 14days). Generally, the safety profile of pegylated filgrastim is similar to that of filgrastim, including skeletal pain, pain at the injection site, palpitation, fever, and fatigue. Conclusion:A single dose of pegylated filgrastim demonstrated comparable efficacy with10consecutive doses of filgras-tim as prophylaxis for chemotherapy-induced neutropenia.