Abstract: Objective: To establish the method for detection of phagocytosis of muirne neutrophils by flow cytometry.Methods: Staphylococcus aureus (S.aureus) and Escherichia coli (E.coli) were labeled with fluorescein isothiocyanate(FITC) in different buffers.The efficient rate of labeling was assessed by flow cytometry.Whole blood taken from mice were incubated with FITC labeled bacteria at 37℃ for 10-20 min,followed by lysing red blood cells.The fluorescent intensity of neutrophils was measured as phagocytotic rate by flow cytometry.Results: The good labeling of S.aureus and E.coli were obtained in PBS(pH 7.2) and carbonate buffer(pH 9),respectively.The percentage of phagocytosis of E.coli was higher than that of S.aureus by murine neutrophils.Conclusions: Detection of phagocytosis of FITC labeled E.coli by flow cytometry is simple,rapid and reproducible method for measuring phagocytotic activity of murine neutrophils.