The maJor components of a dichloromethane extract of mature Eucalyptus delegatensis leaves were cis- and trans-p-2-menthen-l-01, trans-piperitol, a- and /3-eudesmol, 4-phenyl-2-butanone and methyl cinnamate. The major terpenoid was considered to be trans-piperitol, which was responsible for the peppermint aroma of freshly crushed leaves. The steam distdlate of the same leaves contained the above compounds together with a number of monoterpene hydrocarbons which were considered to be artefacts. Use of these hydrocarbons as chemotaxonomic markers was considered to be erroneous.