We report a 52-year-old Japanese woman who developed dyskinesia, epilepsy, and gait disturbance. She was well until 35 years of age, when she noted the onset of gait disturbance. She also noted abnormal involuntary movements in her limbs. She also noted dysarthria at age 38. A neurologist examined her at age 41. The neurologist found cerebellar ataxia and dyskinesia. The atrophy of the brain stem and the cerebellum was on CT. She started to have generalized convulsion with loss of consciousness. Dementia became apparent at age 40. In October, 1993, she became psychotic in which she behaved violently taking off her clothes shouting as "Fire". She was treated with major tranquilizers and became quiet. However, choreic movements became prominent. Her subsequent course was complicated with dysphagia, dementia, convulsion, and frequent bouts of pneumonia. She expired on January 24, 2000 after developing pneumonia. Her father and one sibling had similar motor disturbances. She was discussed in a neurological CPC. The chief discussant arrived at conclusion that the patient had dentatorubral-pallidoluysian atrophy. Most of the participants agreed with this diagnosis. Postmortem examination revealed that entire brain looked smaller than normal including the brain stem and the cerebellum. The cerebellar dentate nucleus showed loss of neurons and gliosis; glumose degenerations were also seen. The external segment of the pallidum showed neuronal loss and gliosis. The subthalamic nucleus showed gliosis without neuronal loss. A demyelinated focus was found in the pons; the lesion looked similar to central pontine myelinolysis. The cerebral white matters were unremarkable. Other areas were unremarkable. The pathological diagnosis was dentatorubral-pallidoluysian atrophy. The pathologic lesion which might explain her dementia was not apparent.