Abstract The chemical compositions of essential oils obtained by hydrodistilation from leaves of Calyptranthes microphylla B. Holts & M.L., Myrcia aff 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, β-pinene (48.4%) and β-bisabolene (12â0%) being the major components, while the essential oils of M. aff fosteri contained 38 compounds, α-bisabolol (19.2%) and β-bisabolol oxide (19.2%) being the principal components. From the essential oil of E. octopleura 40 components, consisting principally of α-pinene (43.0%) and limonene (23.6%) were identified. The oil from Myrcia aff fosteri showed activity against Staphylococcus aureus and Bacillus subtilis, which was comparable to chloramphenicol.