Various sites within the limbic system, frontal lobe and lateral hypothalamus of the rhesus monkey brain were electrically stimulated using chronically implanted electrodes. Increases in plasma cortisol was observed after stimulation of the lateral hypothalamic area, basolateral amygdala, pyriform cortex, hippocampus, certain sites in the cingulate gyrus and orbital part of the frontal lobe. Inactive sites included the caudate nucleus, putamen and white matter in the frontal lobe.