AbstractSeeds of Prosopis alpataco, P denudans var denudans, P denudans var patagonica and P denudans var stenocarpa were analysed for fatty acids and sterols. The seed lipids contained a relatively large proportion of unsaturated fatty acids, with linoleic and oleic acids being predominant. β‐Sitosterol was the major steroid in all species studied. In P alpataco seeds, stigmasta‐1,3,5‐triene and stigmasta‐4,6‐dien‐3‐one were also identified. Copyright © 2003 Society of Chemical Industry