Xeroderma pigmentosum (XP) is an inherited disease with defective DNA repair. Patients develop skin cancer because of unrepaired DNA damage produced by the ultraviolet radiation (UV) in sunlight. Many XP children also develop XP neurological disease (ND), consisting of sensorineural hearing loss (SNHL) and a primary neuronal degeneration of the central and peripheral nervous systems. Since the harmful UV in sunlight cannot reach the nervous system, the cause of the death of XP neurons has been hypothesized to result from the inability to repair their DNA that has been damaged by endogenous metabolites. Progressive XP ND originating in an adult has been identified in only a single case. Although clinically asymptomatic at the age of 47 years, the patient had audiometric evidence of a developing mild SNHL together with elicited signs and electrophysiologic evidence of a peripheral neuropathy. She died of metastatic endocervical adenocarcinoma at 49 years of age. We describe here the neuropathological findings in this patient, including examination of the inner ear. Despite clinical evidence of SNHL, there were no anatomic abnormalities of the inner ear. However, the dorsal root ganglia (DRG) showed ongoing neuronal loss. Our findings indicate that XP ND originating in this adult is, like XP ND in children, a primary neuronal degeneration that manifests first in the peripheral nervous system.