A study was made of the influence of adrenaline of certain components-of the transepithelial sodium transport system in the frog skin and on energy sources-providing its activating effect. Adrenaline proved to increase the sodium transport through the frog skin decreasing its electrical resistance. Strophanthin К prevented the reaction of frog skin to adrenaline completely. Monoiodacetate also produced an inhibitory action on the adrenaline effect which was eliminated on addition of pyruvate into the solution. Potassium cyanide and 2,4-dinitrophenol considerably weakened the adrenaline stimulation of transepithelial sodium transport. A conclusion was drawn that an increase of sodium transport by the frog skin in the action of catecholamines was associated with increase of its ionic permeability and the activation of the ionic pump. It is supposed that the principal source of energy provision for the stimulating effect of catecholamines, were processes of aerobic energy metabolism.