A 70-year-old man had frequent syncope and faintness when in an upright position. A diagnosis of primary orthostatic hypotension was obtained by a head-up tilt test and various autonomic nerve function tests. No abnormalities were seen on myocardium scintigraphy using <sup>201</sup>Tl. However, <sup>123</sup>I-metaiodobenzyl-guanidine did not accumulate in the heart. This suggests that globally denervated myocardium may impair a prompt increase in cardiac contractility and fail to maintain cerebral blood flow, thereby contributing to postural hypotension in this disorder.