A positron emission tomography (PET) study on the regional cerebral glucose metabolism (rCMRglc) was performed in six patients with corticobasal degeneration (CBD). The clinical features included asymmetrical parkinsonism with apraxia, were related to the cerebral cortical and basal ganglionic dysfunction. An MRI study showed all cases to have asymmetrical atrophy in the front-parietal cortex contralateral to the dominantly affected limb; however, no case was pathologically verified. A PET study revealed three cases to have asymmetrical glucose hypometabolism in the parietal lobe and thalamus, which was compatible with the results of previous reports. However, two patients demonstrated symmetrical glucose hypometabolism in the frontal lobe, striatum and parietal lobe while one case had a diffuse hypometabolism, in spite of a marked asymmetry of the neurological findings. These results therefore suggest the heterogeneity of the glucose hypometabolism in CBD based on the PET findings.