Abstract The leaf oils of the 11 recorded Western Australian species of the broombush complex of the genus Melaleuca have been examined by a combination of GC and GC/MS. Melaleuca atroviridis produced a monoterpenic leaf oil with α-pinene (11.0%) and 1,8-cineole (73.2%) being the principal components. Melaleuca concreta showed the presence of three chemotypes, one of which was rich in terpinen-4-ol (35.4%), while a second was rich in 1,8-cineole (58â81%). A third chemotype contained signifcant amounts of α-pinene (16.7%), 1,8-cineole (28.4%) and globulol (11.3%). Melaleuca exuvia produced a monoterpenic oil, which appeared to exist in two chemotypes, which contained α-pinene (13â23%), 1,8-cineole (56â67%), terpinen-4-ol (0.1â2%) and α-terpineol (3â7%) in one form and α-pinene (5â7%), 1,8-cineole (28â38%), terpinen-4-ol (11â17%) and α-terpineol (3â4%) in the second form. Melaleuca hamata produced a leaf oil that was dominated by monoterpenes. There appeared to be two chemotypes present, one in which terpinen-4-ol (41.6%) was the major component and a second chemotype in which 1,8-cineole (40.0%) and linalool (33.9%) were the principal components. Melaleuca interioris (from one population) contained a mixture of mono- and sesquiterpenes, in which sesquiterpenes predominated. Melaleuca osullivanii gave a leaf oil in which sesquiterpenes predominated, the principal component being spathulenol (10â18%). Melaleuca scalena produced a leaf oil dominated by monoterpenes, with α-pinene (25â31%) and 1,8-cineole (43â55%) being the principal components. Melaleuca stereophloia was dominated by monoterpenes of which the principal component was 1,8-cineole (78â83%). Melaleuca uncinata sens. strict. existed in a variety of forms one of which had major amounts of 1,8-cineole (44â56%), while a second contained major amounts of terpinen-4-ol (21â31%), γ-terpinene (10â14%) and α-terpinene (6â8%). Melaleuca vinnula appeared to exist in two chemotypes, one of which was rich in α-pinene (65.3%), while the second chemotype was rich in 1,8-cineole (60.6%). Melaleuca zeteticorum produced a leaf oil that was overwhelmingly monoterpene in character, the principal component being 1,8-cineole (63â68%).