Received em: 20/10/10 | Revised em: 29/11/10 | Accepted em: 01/12/10 | Available online: 22/12/10

The chemical composition of the essential oil (EO) obtained by hydrodistillation from the leaves of Alternanthera brasiliana (L.) Kuntze (Amaranthaceae) is reported herein. The EO extraction process resulted in very low yield (<0.01 % w/w), and washing with ethyl ether was necessary, in order to remove traces of EO from the internal walls of the Clevenger-type apparatus. Twenty-five compounds were identified by GC-MS. 2,6-di-t-butyl-4-methylphenol (42.16%), as well as geraniol (9.15%), aristolene (6.15%), -eudesmol (10.58%), and geranyl tiglate (8.21%) were the major constituents. This is the first report on the chemical composition of the EO from A. brasiliana.