The influence of glucocorticosteroids (cortisone, hydrocortisone, prednisone, dexamethasone, and triamcinolone) on the volumetric natriuresis was studied in experiments on rats. Natriuresis proved to increase considerably after the widening of the extracellular space, and exceeded sodium excretion in control animals after a similar increase of the fluid volume in control animals. Intensification of the natriuretic response to the increase of the extracellular fluid volume against the background of glucocorticoids apparently occurred as a result of production or activation under the influence of these hormone of the natriuretic factor.