Abstract The essential oil from aerial parts of Eupatorium cannabinum L. subsp. cannabinum L. (Asteraceae) was obtained by hydrodistillation. The oil content was 0.37% (v/w), on a dry weight basis. The oil composition was analyzed by GC and GC/MS. Fifty-nine compounds were identified accounting for 94.1% of the oil. Germacrene D (33.5%) was the most abundant component with appreciable amounts of Î±-farnesene (12.9%) and Î´-2-carene (6.5%). Between the oxygen containing components elemol (2.8%) and Î±-cadinol (2.7%) were the most abundant. The oil shows an interesting antibacterial activity, mostly against Gram + bacteria.