We report a 83 year-old woman with dementia. She was apparently well until December of 1993 when she was 81-year-old. At that time, she was operated or her cataract. Her post operative course was uneventful, however, shortly after her operation, she had an onset of memory loss and abnormal behavior. She showed a fluctuating course in her mental disturbance. In 1995, her dementia worsened with nocturnal agitation. She was admitted to our service on June 12, 1995. She was alert and her blood pressure was 140/100 mmHg. She showed recent memory loss and disorientation to time. Motor wise, she was unable to stand unsupported. Her gait with support showed small steps and a wide base. She was bradykinetic and ataxic in her finger-to-nose and heel-to-knee test, however, no rigidity or tremor was noted. Her MRI showed T2-high signal lesions in both medial thalamic areas, in the right occipital lobe, and in the bilateral cerebral white matters as well as in the basal ganglia. She was discharged for out-patient follow up on July 3, 1995. Four days after the discharge, she showed declining responses to stimuli and she developed dyspnea on July 14, 1995. She was admitted again on the same day. Her body temperature was 38.5 degrees C and moist rales were heard in the left lung field. She appeared drowsy and no verbal response was obtained; no apparent motor palsy was noted. Blood count showed leukocytosis (14,300/ml). Blood gas analysis under 61 of oxygen inhalation through a mask was as follows: pH 7.460, PCO2 39.6 mmHg, PO2 67 mmHg, and HCO3-28.5 mEq/l. Two days after admission, she developed a convulsion in her left arm and she became unconscious. Her EEG showed periodically recurring lateralized epileptic discharges on the right fronto-central areas. Her subsequent course was complicated by status epilepticus and respiratory distress. She died on July 26, 1995. She was discussed in a neurological CPC. The chief discussant arrived at a conclusion that she suffered from multi-infarct dementia. Bilateral thalamic infarctions were considered to have played a significant role in her dementia. Post-mortem examination revealed subcortical leukoencephalopathy of Binswanger's type and cerebral infarctions in the thalamic and basal ganglia regions and in the right occipital lobe. In addition, she showed isolated angitis of the central nervous system involving mainly in the small arteries located in the superficial areas of the brain and the spinal cord. This patient was interesting in that despite relatively mild leukoaraiosis in MRI, post-mortem examination revealed profound pathologic changes in the subcortical white matters. In addition, she showed the isolated angitis of the CNS. The cause and the clinical correlates of her angitis were unclear.