Juglone, a highly active allelochemical, is formed in leaves and fruits of walnut trees. It negatively affects oxygene uptake in roots, water uptake and acid efflux in target plants. However, the detailed molecular mechanism of this interaction is still unclear. In the present study we tried to investigate how juglone-treatment affects the phytohormone balance in roots of young pea and corn plants in order to obtain deeper insight in the mode of action of juglone. The test plants were germinated 5 days in vermiculite. Subsequently, they were transferred to aerated hydroponics. The phytohormone signature, including abscisic acid, jasmonic acid, salicylic acid, and various members of cytokinins, was established after 3, 6, 9, 12, 18, 24, 48, and 72 hours, respectively.