Abstract The leaf oils of Eucalyptus chartaboma Nicolle, Eucalyptus miniata Cunn. Shauer and E. gigantangion L. Johnson et K. Hill have been analyzed by a combination of GC and GC/MS. Eucalyptus chartaboma has been found to exist as two chemotypes that are determined by the number of aryl ketones contained in the leaf oil. Chemotype 1 contained isobaeckeol (1-(6-hydroxy-2, 4-dimethoxy-3-methylphenyl)-2-methylpropan-1-one) and homoisobaeckeol (1-(6-hydroxy-2, 4-dimethoxy-3-methylphenyl)-2-methylbutan-1-one), each accounting for approximately 25% of the oil. Chemotype 2 contained nine aryl ketones: apodophyllone (1-(2,4,6-trimethoxy-3, 5-dimethylphenyl)-2-methylpropan-1-one), isotorquatone (1-(2,4,6-trimethoxy-3,5-dimethylphenyl)-2-methylbutan-1-one), torquatone (1-(2,4,6-trimethoxy-3,5-dimethylphenyl)-3-methylbutan-1-one), chartabomone (1-(6-hydroxy-2,4-dimethoxy-3,5-dimethylphenyl)-2-methylbutan-1-one), isobaeckeol, miniatone (1-(6-hydroxy-2,4-dimethoxy-3,5-dimethylphenyl)-3-methyl-butan-1-one), baeckeol methyl ether, homoisobaeckeol and homobaeckeol methyl ether, which together accounted for approximately 50% of the oil. In both cases, the remainder of the oil consisted of terpenes, with α-pinene being by far the major component. Eucalyptus miniata contained only one chemotype, which contained all nine of the above aryl ketones in similar proportions to those in chemotype 2 of E. chartaboma. E. gigantangion did not contain any aryl ketones in its leaf oil, which was composed entirely of terpenes, with α-pinene (45%), limonene (5%), α-terpineol (8%) and borneol (5%) being the principal components. Key Word Index: Eucalyptus miniata Eucalyptus gigantangion Eucalyptus chartaboma Myrtaceaeessential oil compositionisobaeckeolhomoisobaekeoltorquatoneisotorquatonebaekeol methyl etherhomobaeckeol methyl etherapodophylloneα-pinene