abstract the antimicrobial activity of the essential oil of litsea cubeba (lc-eo) and the antimicrobial impact (ai) of individual volatile compounds in the lc-eo on the cariogenic bacteria: streptococcus mutans (s. mutans), streptococcus sobrinus (s. sobrinus) and streptococcus sanguinis (s. sanguinis) were studied. the ai combines the effects of minimal microbicidal concentration (mmc) and quantity of an antimicrobial substance. the ai can quantitatively characterize the relative contribution of individual components of the eo on the entire antimicrobial activity of the eo. for the lc-eo and most volatile compounds investigated, their antimicrobial activities against s. sanguinis were higher than against s. mutans or s. sobrinus. the mmcs of the lc-eo for s. sanguinis, s. mutans and s. sobrinus without biofilms were 375, 750 and 1500 g/ml, respectively. in contrast, the mmc for each strain with the biofilms was double the above value due to the increase of the bacterial resistance. the time-killing study shows that the lc-eo at the mmc for each strain could inactivate >90% of the corresponding bacterial population (initial inoculum of 103 or 105 cfu/ml) within 10 minutes. the good antimicrobial effects within reasonable time of food consumption render the lc-eo applicable in food systems. keywords: antimicrobial activityantimicrobial impact litsea cubeba streptococcus mutans streptococcus sobrinus streptococcus sanguinis