An examination of the function of the hypophyseo-adrenal system was carried out in 31 patients with cerebral stroke by radioimmunoassay of the content of STH, ACTH and cortisol in the arterial and venous cerebral and peripheral blood. The examination showed a demonstrative change of the hormonal balance, especially in the cerebral venous blood that depended on the stroke gravity: this concerned the hormones produced both by the hypothalamo-hypophyseal system and the adrenal cortex. In patients who were in a soporous-comatose state the STH and ACTH content in the cerebral venous blood was lower than in the arterial blood, while the cortisol level exceeded substantially the concentration of this hormone in the arterial blood. A study of the interrelations between the hormones showed that an acute disturbance of the cerebral circulation may induce a response on the part of the hypophyseo-adrenal system. Possible pathogenetic mechanisms of the disturbances of the latter's system function are discussed.