Several fungi including six species of the genus Rhizopogon, 22 species of Hebeloma and one of Agaricus have been screened for production of cytokinins. The screening was done by cul turing cytokinin-requiring soybean callus tissue alongside the fungus on a medium lacking a cytokinin supply. Growth of the soybean callus indicated production of cytokinins by the fungus. Of the fungi tested, only R. ochraceorubens A. H. Smith gave off sufficient cytokinin to be detected. Although a number of mycorrhizal species are now known to make and give off cytokinins, an even larger number apparently do not do so under the conditions of screening employed. An unidentified ectendotrophic species definitely gave off trans-zeatin, which has been crystallized, and probably trans-ribosylzeatin. Suillus punctipes (Pk.) Sing. apparently produced the same two cyto. kinins.The growth patterns of roots in mycorrhizal associations with fungi are commonly different from those of unassociated roots.The suspected roles of auxins, cytokinins, and other plant hormones in these growth modifications recently have been discussed and reviewed quite thoroughly by Slankis (18). Reports from this laboratory have emphasized the possible involvement of cytokinins in the mycorrhizal associations. Both zeatin and ribosylzeatin were crystallized from media in which Rhizopogon roseolus (Corda) Hollos had been cultured and the presumed ribonucleotide was detected (10, 11). Additionally, definite evidence for the production of cytokinins by the mycorrhizal fungi Suillus punctipes (Pk.) Sing., S. cothernatus Sing., Amanita rubescens (Pers. ex Fr.) S. F. Gray, and an unidentified ectendotrophic species was presented (13). We now offer evidence for the identity of cytokinins produced by S. punctipes and the ectendotrophic species and extend the list of species tested for hormone production.