Abstract The essential oil of Ageratum conyzoides leaves was analysed by means of GC and GCâMS; 40 constituentsâ13 monoterpernoids (5.17%), 17 sesquiterpenoids (13.95%) and eight chromenes (71.05%)âwere identified. Two of the chromenes, 6â(1â²â hydroxylethyl)â2,2âdimethyl chromene and 7âhydroxylâ2,2âdimethylchromene, are, reported for the first time as constituents of A. conyzoides . Copyright Â© 2002 John Wiley &amp; Sons, Ltd.