Ravensara aromatica Sonnerat is a tree endemic to Madagascar. The essential oil extracted from the leaves is used in aromatherapy. Previous chemical studies have generated some confusion with regard to the chemical composition of this essential oil. In order to eliminate this uncertainty, we undertook a systematic evaluation of the chemical composition of essential oils from leaves of this species. The study focused on 28 individual samples formally identified as R. aromatica. The essential oils were obtained by hydrodistillation and analysed by GC and GC-MS. It was possible to distinguish four groups of trees through principal components analysis and agglomerative hierarchical clustering analysis of the seven chief molecules identified in their essential oils. Two groups were characterized by a prevalence of compounds with an aromatic structure: methyl chavicol (representing more than 90% of the essential oil) in the first group and methyl eugenol (74-82%) in the second group. The predominant compounds of the other two groups proved to be of the monoterpenic type: a-terpinene (25-28%) and limonene (15-22%) in the third group, while sabinene (25-34%), linalool (7-21%) and terpinen-4-ol (6-12%) were the primary constituents of the essential oils in the fourth group. The importance of these results for the commercial production of the essential oils from this species is discussed. © 2006 John Wiley & Sons, Ltd.