the chemical profile of the essential oils obtained from the leaves and flowers of hyptis passerina mart., a rare species of the brazilian cerrado, has been determined for the first time. analyses by gc-ms showed sesquiterpenes as major compounds. β-epi-acorenol (35.7% and 32.8%, respectively from leaf and flower essential oils), was isolated and identified by 1d and 2d nmr. the flower-derived oil presented a higher concentration of hydrocarbon and oxygenated monoterpenes, while the leaf-oil was richer in diterpenes. the global odour impressions of both oils were given by direct analysis and gc-ms-o and were characterized as herbaceous with tea notes, and green, cooked and woody impressions for leaf-oil; herbaceous, with spicy, woody and minty notes for flower-oil. β-epi-acorenol, spathulenol, β-caryophyllene, and caryophyllene oxide were relevant for the odour-activity of both oils, as well as minor constituents, such as linalool. the antimicrobial activity was investigated by means of agar diffusion disc method and contact bioautography, against gram-positive and negative bacteria and yeast. both oils presented to be bioactive against the tested microorganisms with significant inhibition level.