two aromatic species from the atacama people traditional medicine, aloysia deserticola (phil.) lu-irving & o'leary and artemisia copa phil. var. copa, from antofagasta area (north of chile) were investigated for their essential oils (eo) chemical composition, antioxidant and antimicrobial activity. eo of a deserticola collected in four different spots unexpectedly contained -thujone as the major compound instead of the -isomer described for other chilean and bolivian specimens in the literature. for eo of artemisia copa var. copa, chrysanthenone was the main compound whereas -thujone was identified in a bolivian specimen. these eo exerted no significant antibacterial activity on a panel of forty-four strains, whereas notable inhibition of xanthine oxidase activity was observed with a. deserticola essential oil.