The leaf, stem bark and root bark oils of Isolona cooperi Hutchinson & Dalziel from the Ivory Coast have been analysed by GC (retention index), GC-MS and 13C-NMR spectroscopy. Two types of essential oil were produced by the plant. The leaf and stem bark oils were monoterpene-rich, containing principally (Z)-beta-ocimene and gamma-terpinene and three lactones, 5-[(E and Z)-hexylidene]-5H-furan-2-ones and massoia lactone, were present in appreciable amounts. Conversely, the root bark oil was dominated by 5-isopentenylindole and (E)-beta-caryophyllene. The strategy for the analysis of each oil was adapted according to the nature of the components.