Recently, there has been growing interest and consumption for green tea as healthy beverage. The major biologically active compounds of green tea extract are caffeine and catechins, especially (-)-epigallocatechin gallate that is effective in not only cancer prevention and anticariogenic but also antioxidation.The green tea extract is highly effective in antimicrobial activity against pathogenic bacteria. Antimicrobial activity of ethanol extract of green tea was stronger than that of water extract. The activity is shown against broad spectrum food-borne pathogens, including Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella typhimurium and spoilage bacteria, Bacillus subtilis, Bacillus pumilus and Bacillus cereus. Crude catechin shows also strong antimicrobial effect against oral bacteria, Streptococcus mutans, Acinetobacter baumannii, and Enterobacter aerogenes. Many food products supplemented with green tea extract, such as sausage, chicken, pyeonyuk, steamed bread, yogurt and jelly have been continuously developed and commercially available with improved antimicrobial effect as well as increased shelf life. Key words: green tea extract, antimicrobial activity, food-borne pathogens, oral bacteria