This report concerns an autopsy case of a unique type of multiple system degeneration of the central nervous system. The patient was a Japanese man who was 57 years old at the time of death. The family history did not reveal hereditary burden. His clinical manifestations included deafness in the latter half of the second decade of life, followed by cerebellar ataxia with disturbance of deep sensation. Slight dementia, including psychiatric signs, appeared at the terminal stage of the illness. The neuropathological examination revealed severe degenerative changes in the subthalamic nucleus, substantia nigra, dentate nucleus, superior olivary nucleus, inferior olive, and posterior column. As far as we are aware there is no report of a patient with multiple system degeneration, whose lesions involved such a wide range of anatomical sites as the present case. Because some of his alterations are seen in other disorders, we will address differences between our case and those of other disorders. It is concluded that our patient did not have optico‐cochleo‐dentate atrophy, Friedreich's ataxia, or Machado‐Joseph di