The adrenergic neuroeffector mechanism of blood vessels in Fischer 344 rats was studied from young adulthood to senescence. Norepinephrine (NE) content is maintained through senescence in all veins studied as well as in the superior mesenteric artery. In contrast, NE content declined at 27 months of age in all other arteries studied. Nevertheless, vascular reactivity in vitro to adrenergic nerve stimulation and to NE was well maintained. As to beta-adrenergic responsiveness, this showed a marked decline in arteries from 1 to 6 months of age, but was unchanged in the jugular vein from 3 to 27 months. Overall, then, adrenergic responsiveness of vascular smooth muscle is well maintained in aged rats. However, this study focuses on a discrete aspect of blood pressure control in a species where atherosclerosis is not prominent. Alterations at other sites could be responsible for changes in the overall function of adrenergic cardiovascular control.