Abstract An oil of the piperitone type of Eucalyptus dives produced from trees cultivated in South Africa was analyzed by GC and GC/MS. Seventy-three constituents were characterized with piperitone ranging from 29.2% to 64.9%, depending on whether the oil was produced from dried or fresh leaves. Two novel constituents such as p-menth-5-en-2-one and p-menth-6-en-3-one were characterized as minor constituents of the oil; the former being found in nature for the first time.