A study of the foliage oils of 24 specimens ofHalocarpus bidwillii revealed considerable infraspecific variation. The compounds identified comprised two monoterpene hydrocarbons (α-pinene and myrcene), six sesquiterpene hydrocarbons (α-longipinene, longifolene, caryophyllene, germacrene-D, bicyclogermacrene and δ-cadinene), three oxygenated sesquiterpenes (longicamphenylone, spathulenol, and t-cadinol), six diterpene hydrocarbons [8α-isopimara-9(11),15-diene, sclarene, isophyllociadene, isokaurene, phyllocladene and kaurene] and one oxygenated diterpene (kaur-16-en-19-al). Marked differences between the constitution of the mature and juvenile foliage were noted. © 1990 Pergamon Press plc.