The hydroxyamino moiety of the ferrichrome compounds has been characterized as L-2-amino-5-hydroxyaminovaleric acid (δ-N-hydroxy-L-ornithine). Both ferrichrome and ferrichrome A contain three residues of this new amino acid which together with three residues of glycine (ferrichrome) and one residue of glycine plus two residues of serine (ferrichrome A) are contained within a cyclic hexapeptide. Tentative total structures for the ferrichrome compounds have been proposed.