The fatty acid composition, tocopherol and tocotrienol content, and oxidative stability of petroleum benzene-extracted Gevuina avellana Mol (Proteaceae) seed oil were determined. Positional isomers of monounsaturated fatty acids were elucidated by gas chromatography-electron impact mass spectrometry after 2-alkenyl-4,4-dimethyloxazoline derivatization. This stable oil (Rancimat induction period at 110°C: 20 h) is composed of more than 85% monounsaturated fatty acids and about equal amounts (6%) of saturated and polyunsaturated (principally linoleic) fatty acids. Unusual positional isomers of monounsaturated fatty acids, i.e., C 16:1 ∆ 11 , C 18:1 ∆ 12 , C 20:1 ∆ 11 , C 20:1 ∆ 15 , C 22:1 ∆ 17 , and presumably C 22:1 ∆ 19 were identified. The C 18:1 ∆ 12 and C 22:1 ∆ 19 fatty acids are described for the first time in G. avellana seed oil. While only minute quantities of α-, γ-tocopherols and β-, γand δ-tocotrienols were found, the oil contained a substantial amount of α-tocotrienol (130 mg/kg). The potential nutritional value of G. avellana seed oil is discussed on the basis of its composition. FIG. 1. Flame-ionization detection (FID) gas chromatogram for the fatty acid methyl ester (FAME) mixture of Gevuina avellana seed oil.