The chemical composition of the essential oils of aerial parts and flowers of Chromolaena odorata (L.) R. M. King & H. Rob., collected from Western Ghats region, were obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). Fifty two and thirty four compounds were identified from aerial parts and flowers, representing 94.9 % and 95.2 % of the total oils, respectively. The essential oil from aerial parts was dominated by pregeijerene (14.2 %), epi- cubebol (9.8 %), cubebol (8.6 %), cis-sabinene hydrate (5.7 %), 10-epi-γ-eudesmol (3.8 %), germacrene-D-4- ol (3.6 %) and δ-cadinene (3.5 %), while germacrene D (24.8 %), geijerene (12.6 %), pregeijerene (12.5 %), cyperene (7.8 %), 10-epi-γ-eudesmol (4.7 %), α-muurolol (3.6 %) and khusimone (3.4 %) were identified as the major constituents of flowers oil of C. odorata.