In view of the role of the amygdala in the modulation of adrenocortical secretion we have studied the neural pathways which mediate this response. Changes in plasma corticosterone following medial amygdala stimulation, under pentobarbital anaesthesia, were studied in rats which chronically implanted electrodes in intact and lesioned animals. The rise in plasma corticosterone following amygdala stimulation was inhibited by bilateral lesions of the stria terminals, medial preoptic area, and bed nucleus of the stria terminalis, and to a greater extent by a combined lesion of the latter two structures. The combined lesion also completely blocked the adrenocortical response to olfactory stimulation. These various lesions did not affect, however, the rise in plasma corticosterone following ether stress. These data thus demonstrate that the stria terminalis, preoptic area and bed nucleus of the stria terminalis are involved in the transmission of neural impulses to the hypothalamus which activate adrenocortical secretion.