The maturity of the hypothalamic-neurohypophyseal system in the first 10 days of the postnatal life of rats was analysed through the potential inhibitory effect of ethanol on oxytocin and vasopressin secretion. Experimental animals were intraperitoneally injected with ethanol, and the control ones with the corresponding amount of physiological solution. Hypophyses were extracted 30 min later to be histologically analysed. Although the morphological features of neurohypophysis with functionally active pituicytes and dense vascular net were present even from the first natal day, neurosecretory grains were noticed not before the 8 th day. But the inhibitory effect of ethanol on neurosecretion did not manifest itself until the 10 th day, so it can be concluded that in this period the hypothalamic-neurohypophyseal system had not yet reached its level of complete maturity. Fatty acids in pituicytes being elements of neurohypophyseal neuroglia are pronunced even in animals younger than 10 days, which indicates that their origin could not be necessarily linked to the process of neurosecretion. In acutely alcoholized offsprings the amount of fatty acids in the neurohypophysis was reduced. This is substantiated by the engagement of the alcohol dehydrogenase (ADH) and the microsomal ethanol-oxidizing system (MEOS) in alcohol metabolism with which follows retarded oxidation process of fatty acids.