The properties of two enzymes involved in the shikimic acid pathway, dehydroquinate hydro-lyase and shikimate: NADP(+) oxidoreductase were studied in different species of higher plants (pteridophytes, gymnosperms, angiosperms) using chromatography on Sephadex G 100, DEAE cellulose, hydroxylapatite and isoelectric focusing.The two enzymes were not separable by these methods, and we conclude that they exist as an aggregate in higher plants. Moreover, the behaviour of the complex is sometimes quite different according to the species, and these data support the notion of alloenzymes.This situation seems contrary to that found in procaryotic organisms in which all the enzymes of the pathway are separable and in fungi in which five enzymes are associated.These results are discussed in relation to evolution, the channeling function of such complexes and the metabolism of quinic acid in plants.