Staphylococcal food poisoning is the major cause of bacterial fl∞d poisoning. Chlorination has been one of the most adpoted inactivation processes for the drinking water. But several disadvantages of chlorination include the formation of undesired halogenated by-products and low inactivation efficiency of chlorine-resistant pathogenic microorganisms. The purpose of this study was to examine the disinfection efficincies of Staphylococcus aureus by ozone and gamma ray. The disinfection efficiency of ozone was 86.08% at 5 min. Gamma radiation showed the disinfection efficiency of 88.15% at higher than O.2kGy. Microbial regrowths after ozone and gamma ray disinfections were also evaluated for 4 days. Significant microbial regrowth was observed for ozone disinfection, while there was almost no microbial regrowth for gamma ray disinfection at O.2kGy.