In vitro activity of Sarafin® (sarafloxacin hydrochloride) was determind againts 7 luminous Vibrio harveyi isolates and 3 non-luminous Vibrio species (V. parahaemolyticus, V. alginlyticus and Vibrio species) isolated from diseased marine shrimp (Penaeus monodon) and rearing water, a strain of V. anguillarum from diseased marine fish, I strain each of V. alginolyticus, V. vulnificus, and V. mimicus from diseased grouper (Epinephelus coioides), and V. alginolyticus from diseased seabass (Lates calcarifer). Bacterial susceptibility was expressed as minimum inhabitory concentration (MIC) and minimum bactericidal concentration (MBC). The MIC and MBC values obtained for all V. harveyi isolates ranged from <0.3 to 1.25µg/ml. For the non-luminous vibrio species, MIC and MBC values ranged from <0.08 to 1.25µg/ml. In vivo tolerance level (24 h static bioassay) of larval and postlarval stage of P. monodon for Sarafin® were ≤10 µg/ml for nauplii, mysis, and postlarvae and ≤1 µg/ml for zoeae. Morphological deformities in the carapace, rostrum, and setae were noted among larvae exposed to ≤50 µg/m Sarafin®. These results indicate that Sarafin® is a potential candidate as a chemotherapeutic agent againts luminous vibriosis in P. monodon.