chemical composition and antibacterial activity of essential oils from three endemic plants including, thymus daenensis celak, dracocephalum multicaule montbr & auch., satureja bachtiarica bunge and one native plant, tanacetum polycephalum schultz-bip were determined. volatile oils analyzed using gas chromatography and gas chromatography-mass spectrometry. the in-vitro antibacterial activity was performed by agar disc diffusion and micro-dilution assays. the results revealed distinct differences in the compounds depending on sample plant. among the plant species screened, essential oils of s. bachtiarica and t. daenensis showed highest antibacterial activity against staphylococcus aureus.