abstract the chemical compositions of essential oils obtained by hydrodistilation from leaves of calyptranthes microphylla b. holts & m.l., myrcia fosteri croat and eugenia octopleura krug & urb, belonging to family myrtaceae were studied by gc and gc/ms. forty-three compounds, representing 93.5% of the total, were identified in c. microphylla, -pinene (48.4%) and -bisabolene (12-0%) being the major components, while the essential oils of m. aff fosteri contained 38 compounds, -bisabolol (19.2%) and -bisabolol oxide (19.2%) being the principal components. from the essential oil of e. octopleura 40 components, consisting principally of -pinene (43.0%) and limonene (23.6%) were identified. the oil from myrcia fosteri showed activity against staphylococcus aureus and bacillus subtilis, which was comparable to chloramphenicol.