The post-antibiotic effects (PAE) of DW-116 were evaluated against Bacillus subtilis ATCC 6633, Bacillus cereus ATCC 27348, Staphylococcus aureus ATCC 25923 , Escherichia coli ATCC 25922 and Pseudomonas aeruginosa MB4-16, repectively. Against gram-positive bacteria, PAEs of DW-116 were longer duration (20-35 min) than those of rufloxacin(1O-20 min), and shorter than those of ciprofloxacin (50-90 min). Especially, against E. coli, DW-116 and ciprofloxacin obtained approximately 3 hrs of PAES.