A 49-year-old female with no history of hearing disturbance developed sudden onset of headache and was admitted with no neurological deficits other than mild nuchal rigidity. Computed tomography (CT) showed subarachnoid hemorrhage. Four-vessel cerebral angiography disclosed no aneurysm. A second angiogram obtained on the 14th day showed vasospasm of the bilateral posterior cerebral arteries and right anterior inferior cerebellar artery, but still failed to demonstrate an aneurysm. Following the second angiography, she developed mild disturbance of consciousness and cerebellar ataxia of the right limbs, and repeat CT showed an infarct in the right cerebellar hemisphere. When she regained consciousness a few days later, she was completely deaf on the right side. The third angiography revealed a right vertebral artery dissecting aneurysm. Following clipping of the proximal portion of the right vertebral artery, she did well and was discharged, although right cerebellar ataxia and deafness persisted. Neuro-otological evaluation, including pure-tone audiography, auditory brainstem responses, electrocochleography, and caloric testing, indicated that her deafness resulted from ischemia in the territory of the right internal auditory artery due to vasospasm.