We have investigated the constituents of the essential oil of Cyperus alopecuroides. Three new compounds, the hydrocarbon, (-)-eudesma-2,4(15)-11-triene, the sesquiterpene alcohol (-)-eudesma-3,11-dien-5-ol and the diterpene hydrocarbon (-)-dolabella-3,7,18-triene were isolated and their structure elucidated.