Adrenal venous blood was analyzed for corticosteroid content in various dog preparations. Dogs with brain removal down to the pons and isolated pituitaries exhibited a period of depressed adrenal cortical function, followed by persistent elevated “resting” secretion. Removal of the entire brain and spinal cord in addition did not alter this response, nor did removal of the posterior pituitary or abdominal evisceration. Similar patterns of adrenal cortical function were present in dogs with hypothalamic islands.