Essential oil extracted from dried aerial parts of Teucrium flavum ssp. flavum harvested in Zakynthos, Greece, was analysed by gas phase chomatography (GC) and gas chomatography mass spectrometry (GC-MS). The main constituents were caryophyllene (13.5%), caryophyllene oxide (8.5%), 4-vinyl guaiacol (6.0%) and alpha-humulene (5.0%).