abstract the leaf oils of the four species of waterhousea have been investigated by gc and gc/ms. waterhousea floribunda gave a variable oil that in most cases was dominated by - and -pinene (17-21%), while at the other extreme the major compounds were sesquiterpenes, with no one compound predominating. w. hedraiophylla gave an oil dominated by sesquiterpenes with spathulenol, calamenene, -cadinene and bicyclogermacrene being the principal components. w. unipunctata also gave a sesquiterpenic oil with germacrene d (8.2-25.6%), bicyclogermacrene (3.2-12.3%), globulol (0.4-15.8%) and viridiflorol (0.2-9.6%) being the principal components. apart from containing both mono- and sesquiterpenes, waterhousea mulgraveana oil also contained mixtures from 1,3,5-trimethoxybenzene, 2,4,6-trimethoxyethylbenzene, 2,4,6-trimethoxystyrene and 2,4,6-trimethoxy-3,5-dirnethylstyrene.