During performance of pituitary neuroadenolysis for relief of cancer pain, metrizamide solution was injected through the same needle used for ethanol instillation into the sella turcica in 8 cases. In half of the cases, the contrast material flowed out along the pituitary stalk immediately after it reached the sellar cavity, and delineated the third ventricle, the aqueduct, and the fourth ventricle, suggesting spread of ethanol along the same route. Autopsies performed in 18 cases which had been subjected to neuroadenolysis revealed widespread necrosis in all pituitaries, but no gross or histological alterations were observed in any of the hypothalamus, thalamus, brain stem, or pituitary stalk, except for a localized necrotic focus in the stalk and/or infundibulum in one-third of the cases. These findings indicate that the ethanol instilled into the sella turcica induces necrosis of the pituitary gland, and also acts as a destructive as well as a stimulative agent on the nervous structure around the ventricle. It is assumed that cancer pain is relieved through these effects of ethanol on the hypothalamopituitary axis which would influence the related structure of the central nervous system.