Thyroliberin increases the cerebral blood flow both in anesthesized cats and unanesthetized rabbits under hemorrhagic shock. At the same time the increase of the arterial pressure is observed, caused by activation of the sympathoadrenal system. This is confirmed by experiments with the removal of the hypertensive reaction to thyroliberin after the use of the alpha-adrenoblockers. Analysis of the action mode of thyroliberin on the cerebral circulation with the use of atropine, dihydroergotoxin and propranolol allowed one to establish the involvement of beta-adrenoreceptors of the cerebral vessels in mediation of the cerebrovascular effect of the drug. The thyroliberin ability to improve the cerebral circulation under pronounced hypotension as well as to make the arterial pressure return to normal underlies its positive effect on the lifespan of animals under hemorrhagic shock.