The leaf oils of the 14 Australian species of the genera Euodia and Melicope have been analyzed by GC and GC/ MS. Euodia hylandii produced a leaf oil that was dominated by sesquiterpenes, with spathulenol (12-20%) as the major component. Euodia pubifolia gave a primarily sesquiterpenic oil with the major component being spathulenol (18.3%). Melicope affinis produced a sesquiterpenic oil in which the major components were the hydrocarbons bicyclogermacrene (7-18%) and β-bisabolene (t-9%). Melicope bonwickii gave an oil in which sesquiterpenes predominated; zierone (0.3-3%) and three further suspected isomers (A, B each 5-10% and C 13-20%) were the principal components. The leaf oil of M. broadbentiana was, in most cases, dominated by monoterpenes. The major components detected were α-pinene (21-76%) and limonene (0.6-28%). Melicope elleryana gave a leaf oil which was dominated by zierone (26-42%) and the chromenes, allo-evodione (4-10%) and evodione (10-22%). Melicope fellii produced a sesquiterpenic oil with the principal components being β-caryophyllene (9.9%), α-humulene (8.4%) and caryophyllene oxide (7.4%). Melicope hayesii produced an oil which was sesquiterpenic in nature. The principal components were bicyclogermacrene (22.8%), germacrene D (13.9%), (E,E)-α-farnesene (9.2%) and globulol (10.6%). Melicope jonesii also produced a complex sesquiterpenic oil with no one compound predominating. The leaf oil produced by M. micrococca was variable, with the major components being α-pinene (1-46%), (E)-β-ocimene (t-10%), β-caryophyllene (0.4-15%), bicyclogermacrene (t-11%), caryophyllene oxide (0.3-23%) and spathulenol (1- 12%). The leaf oil of M. peninsularis was dominated by sesquiterpenes, with the principal components being β-caryophyllene (30-49%) and α-humulene (26-35%). Melicope rubra gave a leaf oil containing significant amounts of both mono- and sesquiterpenes. Sabinene (31.1%), γ-terpinene and germacrene D (22.6%) were the principal components. The principal monoterpenes were sabinene (0.1-54%, the majority > 25%) and limonene (1-47%, the majority < 2%). These were also the principal components of M. vitiflora. The leaf oil of M. xanthoxyloides contained major amounts of sesquiterpenes, though monoterpenes could contribute up to 20% of the oil. The principal components were β-caryophyllene (13-47%), spathulenol (1-18%) and α-pinene (t-15%).