SummaryEectric stimulation of the hypothalamus elicits an immediate systemic pressor reaction and a tenfold increase of adrenalme- and noradrenaline-concentration in venous blood of anaesthetized dogs. During the hypothalamic simulatlon, a slight increase of catecholamines occurs in the femoral venous blood returning from the pump-perfused hind leg. The induced hypertension is accompanied by a slight femoral vasoconstriction or even by a femoral vasodilatation in some cases. The haemo dynamic and biochemical findings clearly indicate that the femoral circulation has only a minor participation in the general orthosympathetic cardiovascular effect of hypothalamic stimulation.