Abstract： Objective To determine the mutant prevention concentration (MPC) of 6 kinds of fluoroquinolones for the clinical isolated coagulase negative staphylococcus,and to compare the 6 kinds of fluoroquinolones.Methods The minimal inhibitory concentrations (MIC) and the mutant prevention concentration (MPC) of ciprofloxacin,levofloxacin,gatifloxacin,cadrofloxacin,moxifloxacin and pazufloxacin were determined with 34 strains of coagulase negative staphylococcus isolated which were sensitive to oxacillin and ciprofloxacin by agar two-fold dilution method and ager plates dilution method.Results For MPC9o,moxifloxacin was the lowest (1 mg/L).Cadrofloxacin,gatifloxacin and pazufloxacin,levofloxacin and ciprofloxacin were the highest among the 6 kinds of fluoroquinolones against coagulase negative staphylococcus which were 32 mg/L; as for MIC90/MPC90,moxifloxacin,cadrofloxacin and gatifloxacin were lower; pazufloxacin,levofloxacin and ciprofloxacin were higher.The comparison of the pharmacokinetics parameter in vivo for the 6 kinds of fluoroquinolones against the 34 strains of coagulase negative staphylococcus showed that MPC90 was less than Cmax for moxifloxacin and cadrofloxacin,and was similar to gatifloxacin.Conclusion Moxifloxacin,cadrofloxacin and gatifloxacin have a lower MPC and narrower mutant selective window with a high ability to restrict the selection of coagulase negative staphylococcus resistant mutants among the 6 kinds of fluoroquinolones against the coagulase negative staphylococcus.