Free amino acids and y-glutamyl peptides have been examined in 22 species of Iridaceae. 3-(3'-carboxyphenyl)alanine and 3'-carboxyphenylglycine, previously known from the tribes Irideae and Tigridideae in the subfamily Iridodeae have been identified also in the tribe Mariceae of Iridoideae and the genera Bobartia, Orthrosanthus and LibertJ'a of the subfamily Sisyrinchioideae. y-Glutamyl peptides, previously known from the tribe Irideae, have been found also in the tribe Mariceae, both tribes being from subfamily Iridoideae. y-Glutamyl-S-methylcysteine, y-glutamylmethionine and the corresponding sulphoxides are the dominating ~,-glutamyl peptides in the genera Dietes, Gynandriris, Moraea (tribe Irideae), Neomarica and Trimezia (tribe Mariceae), whereas ~,-glutamyl peptides with non-sulphur amino acids are predominant in genera Ferraria, Hermodactylus, Homer& Iris, Iridodyclyum and Xiphium (tribe Irideae). Dietes robisoniana, endemic to Lord Howe Island, has the same technical characters as other Dietes species from Southern Africa. The results are discussed in relation to botanical classification of and within the subfamilies Iridoideae and Sisyrinchoideae.