The leaf oils from all 23 published and four unpublished species in the genus Homoranthus have been examined. All species produced oils, which were dominated by monoterpenes, accounting for up to 75% of all oils. α-Pinene was usually a major component in all species. (Z)-β-Ocimene was a major component (>40%) in H. biflorus, H. binghiensis, one chemotype of H. cernuus, H. flavescens, H. montanus and H. sp. nov. Nandewar Range. When present in large amounts, it was usually not accompanied by the (E)-isomer. Limonene was the principal component of H. bornhardtiensis, one chemotype of H. decumbens, H. homoranthoides, H. prolixus, and one chemotype of H. sp. nov. Nandewar Range. γ-Terpinene was the principal component of one chemotype of H. decumbens, H. thomasii, H. tropicus and one chemotype of H. sp. nov. Nandewar Range, while methyl geranate was a significant component of H. tropicus. Of the sesquiterpenes found in the leaf oils of the genus, bicyclogermacrene was always a significant component, ranging in amounts up to 30% in individual samples. Globulol was usually the most significant oxygenated sesquiterpene, though never in amounts greater than 10%. Occasionally (E)-nerolidol was present in similar amounts. Oil yields were in the range 0.5-2% w/w (dry weight) over the whole genus.