Infection of the root system in tomato by the root-knot nematode was found to alter the gibberellins and cytokinina extracted from root tissue and xylum exudate. Gibberellins from the root tissue and xylem exudate of healthy plants occurred in the neutral, acidic, and aqueous fractions. With increasing levels of infection, gibberellins were primarily extracted in the slightly acidic fraction. Gibberellin activity in the neutral, acidic, and aqueous fractions was decreased in diseased plants. Cytokinins, which were also extracted from root tissue and xylem exudate, were lower in diseased plants than in uninfected plants.