Abstract The volatile oil of Hyparrhenia rufa (Nees) Stapf. grown in Nigeria was obtained by hydrodistillation and analysed by GC, GCâMS, 1 Hâ and 13 CâNMR. The main components found were Ï âcadinol (17.43%) and Î² âselinene (11.64%). The most interesting characteristic of the oil was the presence of four unusual and rarely occurring terpenoid esters: ( E , E )âmethyl farnesoate (1.01%), ( E , E )âmethylâ10,11âepoxyfarnesoate (12.17%), methyl (2 E ,6 E )â10âhydroxyâ3,7,11âtrimethyldodecaâ2,6,11âtrienoate (4.3%) and methyl (2 E ,6 E )â3,7,11âtrimethylâ10âoxododecadienoate (2.25%). Copyright Â© 2004 John Wiley &amp; Sons, Ltd.