The in vivo and in vivo antibacterial activity of DW-116, a newly synthesized fluoroquinolone, were compared with those of other quinolones. DW-116 exhibited more potent antibacterial activity than rufloxacin and lower activity than ofloxacin and ciprofloxacin in in vivo assay But, DW-116 particularly showed strong activity against the family of staphylococci including methicillin-sensitive staphylococcus and its activity was more active than that of ciprofloxacin. The time-kill curve studies showed rapid bactericidal activity for DW-116. The post-antibiotic effect of DW-116 was observed between 0.66 and 5 hours. The therapeutic efficacy of DW-116 against respiratory infection with P. aeruginosa was as strong as that of ciprofloxacin and its effect against urinary tract in(traction with E. coli was more effective than rufloxacin. The excellent therapeutic efficacy of DW-116 against these local infections is due to its good pharmacokinetic profiles.