scutellaria volubilis and lepechinia paniculata belong to the lamiaceae family of species. they are used widely in traditional medicine in ecuador. the physical properties and chemical composition of the essential oils from the aerial part of scutellaria volubilis in its foliation - flowering stage and lepechinia paniculata in its flowering phase have been studied after their hydrodistillation. the components of these essential oils were investigated by means of gas chromatography/mass spectrometry (gc/ms) and gas chromatography/flame ionization detection (gc/fid) techniques. thirty-seven components were determined in the essential oil of s. volubilis. the principal constituents were found to be sesquiterpene hydrocarbons: germacrene d (20.4%), b-caryophyllene (17.5%), a-humulene (14.7%) and b-bisabolene (5.8%). thirty-four components were identified in the essential oil of l. paniculata, the principal groups were sesquiterpene hydrocarbons such as aromadendrene (24.6%), viridiflorene (12.4%), b-selinene (7.4%) and valencene (6.7%). the monoterpene hydrocarbons were present in lower amounts as well as b-phellandrene (6.9%) and (7.7%). oxygenated monoterpenes and sesquiterpenes contribute below 5% in both species. this is the first report on the chemical composition of this species.(c) 2012 taylor & francis.