The hydrodistilled essential oil of the roots of Chromolaena odorata (L.) R. M. King &amp; H. Rob. was analysed by gas chromatography equipped with flame ionization detector (GCâFID) and gas chromatography coupled with mass spectrometry (GC/MS). A total of twentyânine compounds have been identified, accounting 97.6% of the total oil. The main constituents were himachalol (24.2%), 7âisopropylâ1,4âdimethylâ2âazulenol (17.6%), androencecalinol (14.1%), and 2âmethoxyâ6â(1âmethoxyâ2âpropenyl) naphthalene (5.6%). The essential oil consists mainly of phenyl derivatives (41.6%), followed by oxygenated sesquiterpenes ((26.6%), longâchain hydrocarbons (18.9%), sesquiterpene hydrocarbons (6.8%), oxygenated monoterpenes (2.8%), and monoterpene hydrocarbons (0.9%). This study revealed that the roots of C. odorata produced different chemotypes other than leaves oil. This is the first report on the essential oil composition of the roots of C. odorata .