3-Dehydroshikimate hydro-lyase was extracted and partially purified by ammonium sulfate fractionation from the hypocotyls of etiolatedPhaseolus mungo seedings. The enzyme was most active at pH 7.0 and the Km for DHS was 1.4 mM. Enzyme activity was inhibited byp-chloromercuribenzoate and arsenite, the inhibition being reversed by reduced glutathione. Enzyme activity was found in extracts from young hypocotyls and cotyledons, especially from 5–6 day-old hypocotyls and 3–4 day-old cotyledons. Changes in enzyme activity in both cotyledons and hypocotyls were measured during the early stage of germination. Participation of this enzyme in the catabolism of alicyclic acids is suggested.