Corticotropin-releasing factor (CRF) has been microinjected into different brain areas in an effort to characterize specific sites of action of this peptide to influence the concentrations of norepinephrine in plasma. Although many brain sites were identified to be unresponsive to CRF stimulation there were also an abundant number of sites found where CRF elicited significant elevations of plasma catecholamine concentrations. None of the tissue sites of action of CRF were associated with increases of plasma levels of norepinephrine greater than those following CRF administration into the third ventricle. The results suggest that anatomic redundancy exists for the response to exogenous CRF administration.