Regional cerebral glucose metabolism was measured in a 72-year-old man, with Creutzfeldt-Jakob disease (CJD), by positron emission tomography using [18F]-2-fluoro-2-deoxy-D-glucose as the tracer. The diagnosis of CJD, a rare neurodegenerative disorder, was confirmed at autopsy 13 months later. Compared with five unaffected elderly men, the patient had reduced metabolism heterogeneously distributed throughout the brain. The hypometabolism was most evident in the right hemisphere, particularly in the posterior frontal, parietal, Sylvian, and temporal regions. This left-right asymmetry is more extensive than that previously reported in Alzheimer's disease, and may provide a useful metabolic marker for early diagnosis of CJD.