We report on a 67-year-old male patient with progressive right-sided hemiparesis predominating in the arm and right-sided myoclonias. The EEG showed periodic delta activity in the left hemisphere. The patient died of pulmonary embolism 10 weeks after the onset of the symptoms. The neuropathological examination was indicative of Creutzfeldt-Jakob disease: distinct spongiform changes, nerve cell loss and proliferation of astroglia in the left hemisphere were found; in the right hemisphere, however, only a few circumscribed spongiform foci were seen. There was a clear correlation between the unilateral predominance of the EEG abnormality and neuropathological changes. The hypothesized spread of infection along commissural projection pathways is supported by this pattern of lesions.