Barley and tomato shoots were examined quantitatively for naturally-occurring indole compounds. Both tissues were found to contain detectable levels of indol-3yl-acetic acid (IAA), indol-3yl-aldehyde, tryptamine, 5-hydroxytryptamine and malonyltryptophan. Tomato shoots also contained small amounts of indol-3yl-lactic acid and tryptophol. These two compounds were absent in barley, but this tissue contained significant quantities of 3 -aminomethylindole, 3-methylaminomethylindole, gramine, N-methyltryptamine and 5-hydroxy-N-methyltryptamine. The possible importance of these compounds in the biosynthesis of IAA, or in the formation of alkaloids, is discussed.