abstract this study was designated to evaluate the antimicrobial activity of the essential oils obtained from the aerial parts of origanum minutiflorum and sideritis erytrantha, both endemic species in turkey, against 19 plant pathogenic bacteria. two essential oils were analyzed by gc-fid and gc/ms. the major components of o. minutiflorum oil were carvacrol (73.93%) and p-cymene (7.20%). the essential oil of o. minutiflorum exhibited an extremely strong activity against tested plant pathogenic bacteria such as agrobacterium spp., erwinia spp., rathayibacter spp., xanthomonas spp., clavibacter sp. and curtobacterium sp., but did not show any antimicrobial activity against pseudomonas spp. the minimum inhibitory concentration (mic) values for bacterial strains which were sensitive to the essential oil of o. minutiflorum and s. erytrantha subsp. erytrantha were in the rage of 125-400 ug/ml and 300-500 ug/ml, respectively. key word index: origanum minutiflorum sideritis erytrantha subsp. erytrantha lamiaceaeessential oilplant pathogenic bacteriaantimicrobial activity