The effect of ether stress and dexamethasone on hypothalamo-hypophyseal-adrenal axis was investigated in sexually mature male Wistar rats. Separate group of rats was subjected to ether stress during 2 minutes. The remaining animals were treated with dexamethasone during 7 days. CRF-immunoreactive and vasopressin-immunoreactive neurons were detected within paraventricular nuclei and median eminence by using specific antibodies. Body weight of the rats as well as the weights of pituitary and adrenal glands were also measured. The levels of ACTH and corticosterone were determined in blood serum. It was found that the ether stress caused a considerable decrease in the amount of CRF-immunopositive substances in the outer layer of median eminence and a decrease in the amount of vasopressin-immunoreactive neurocytes in the parvocellular fragment of paraventricular nuclei. Dexamethasone administration caused an increase in the amount of CRF-immunopositive perikaryons within paraventricular nuclei and also an increase in vasopressin-immunopositive nerve fibers in median eminence.