The composition of 27 samples of berry oil and 54 samples of leaf oil of Juniperus oxycedrus ssp. oxycedrus from Corsica was investigated by GC, GC–MS and 13C-NMR. The main constituents were terpene hydrocarbons, especially α-pinene, myrcene and germacrene D in the oils from berries and α-pinene, β-phellandrene and Δ3-carene in the oils from leaves. The results of the analyses were submitted to k-means partitioning and principal component analysis, which allowed the distinction of two compositions in the berry oils (differentiated by the contents of α-pinene, myrcene and germacrene D) and in the leaf oils (differentiated by the contents of α-pinene, β-phellandrene and Δ3-carene). (Z)-6-Pentadecen-2-one, an unusual alkenone present in several samples of leaf oil, was identified using 13C-NMR spectroscopy. Copyright © 2005 John Wiley & Sons, Ltd.