A 77-year-old man suffered intermittent hemiconvulsions of unknown etiology on the left side for a period of about 5 weeks. At the autopsy, there was marked neuronal loss, severe proliferation of astrocytes and spongiform changes in the right cerebral cortex. The cerebral white matter showed loosening with astroglial proliferation in areas on the same side. These neuropathological changes were slight or absent in the left cerebral hemisphere. Histopathological changes were similar to those seen in unilateral Creutzfeldt-Jakob disease (CJD). Although unilateral CJD can not be ruled out, these unilateral hemispheric changes might be induced by intermittent hemiconvulsions.