A perivascular sympathectomy was performed at the base of the ear artery in 11 New Zealand white rabbits. Two days later three were killed, and the central nerve was cut in the remaining eight. The contralateral ear served as a control. Specimens were taken from the distal parts of both ears two days later and the glyoxylic acid-induced fluorescence method was used to show the adrenergic nerves. The arteries of the normal, control ear were surrounded by a dense plexus of fluorescent adrenergic nerves, which were abolished by perivascular sympathectomy only in the segment from which the adventitia had been removed. The adrenergic innervation was normal proximal to the site of perivascular sympathectomy, but there was a short segment of the central vessel distally in which it was diminished. No changes in adrenergic innervation were found in the distal third of the rabbit ear.