The contents of cytokinins and abscisic acid in the shoots and roots of 8-day wheat seedlings were studied by enzyme immunoassay in conditions of heating from 24 to 35 degrees C and after returning to the initial conditions. Two peaks of abscisic acid content in the aerial plant organs accompanied by decreased content of active cytokinin (zeatin) were observed at the beginning and at the end of heating. We propose that antiphase changes in zeatin and abscisic acid concentrations should enhance the same effects, for example, stomatal closure.