Although it has been stated that denervation of vascular smooth muscle results in little mor phological change (13, 19), there is some evi dence for a trophic influences of the autonomic nerves on smooth muscle (1)—an effect well documented for striated muscle (6, 10, 15, 16). Chronic sympathetic denervation was found to reduce the number of smooth muscle cell nuclei of the growing rabbit ear artery incorporating 3H-thymidine (a DNA precursor) suggesting that the sympathetic adrenergic innervation in fluences the proliferation of vascular smooth muscle during growth (3). One consequence of this action might be a smaller blood vessel capable of generating a lower maximum force. To examine this possibility the effect of long term sympathetic denervation on maximum contractility, size, elasticity and weight of an artery was examined.