Abstract The essential oils of three Australian species of the genus Cassytha have been investigated using GC and GC/MS. Cassytha filiformis produced an oil that was sesquiterpenoid in nature, with bicyclogermacrene (12â26%), spathulenol (27â36%) and Î²-caryophyllene (5â10%) being the principal components. Cassytha pubescens appeared to exist in several chemical types. A Principal Components Analysis of the oils appeared to indicate that there were three chemical types present in the 13 collections. The first variety contained (E)-nerolidol (26.7%) and Î²-caryophyllene (23.5%) as major components. The second chemical variety of this species showed elevated levels of Î±-copaene (4â6%), moderate amounts of Î²-caryophyllene (8â14%), caryophyllene oxide (3â17%) and bicyclogermacrene (2â9%), and high levels of spathulenol (27â32%). The third variety was more variable and contained significant amounts of spathulenol (4â21%), bicyclogermacrene (2â40%), Î²-caryophyllene (1â31%), and aromadendrene (0.7â10%). The principal component of C. capillaris oil was spathulenol (31%). The oil yields, in all species, were 0.1% or less.