Biopsy specimens of vestibular nerves of 40 patients with severe Meniere's disease were studied by microscopy. In 17 patients, a translabyrinthine eighth nerve transection was done; in 23 patients, a middle fossa vestibular neurectomy was done. Many of the nerve fibers had thickened and deformed myelin coats; some were thinly myelinated fibers and some showed degraded myelin. No macrophages were present. Occasional vestibular ganglion cells had thin myelin coats. In six patients, there were lighter areas between the fibers. In these there were roughly parallel astrocyte processes, with numerous cytoplasmic filaments. The light areas were surrounded by a basement membrane. Four of these patients showed continuation of vertiginous symptoms after operation and were not helped by surgery. These patients may suffer from a neuropathy that is different from the more common causes of Meniere's disease.