Antimicrobial activity and chemical composition of volatile flavor extracts from Agastache rugosa were investigated. The volatile flavor extracts were obtained from leaves and stems of Agastache rugosa by simultaneous distillation extraction (SDE) method. Antimicrobial activity was investigated by disc diffusion and broth dilution methods against several microorganisms of Bacillus cereus, bacillus megaterium, Bacillus subtilis, Corynebacterium xerosis, Staphylo coccus aureus, Staphylococcus epidermidis, Agrobacterium rhizogenes , Agrobacterium tumefaciences, Enterobacter cloacae, Escherichia coli, Salmonella typhi, Vibrio parahaemolyticus, Candida utilis and Saccharomyces cerevisiae. Volatile flavor extractsfrom leaves have strong antimicrobial activity against C.utilis and S.cerevisiae. When 0.12% volatile flavor extracts from fresh leaves were included in the medium, lag phase of C. utilis was extended 6 hr and that of S.utilis and S.cerevisiae was extended 2hr. Further analyses were performed to elucidatethe effective component of the extracts. The major component of volatile flavor was estragole, a phenolic compound. Minor components were determined to be terpenes , alcohols, acids , esters, ketones and aldethydes.