Regional brain glucose metabolism was studied with positron emission tomography (PET) in healthy volunteers (n = 9) and schizophrenic patients (n = 15). The patients were in an acute phase of the disease and drug free. Cerebral metabolic rate with 11C-glucose as the tracer (CMRgl) was determined in both cortical and subcortical structures. In the healthy volunteers significant correlations were found between metabolic rates of some regions, but no relationships were found between CMRgl of limbic cortical areas and that of neocortical or subcortical structures. In the patients, high and significant positive correlations were found between metabolic rates in the neocortical areas, the limbic cortical areas and the subcortical areas. The results indicate differences in the neuronal interplay between regions of healthy and schizophrenic subjects. It is proposed that neuronal systems guiding the specificity and diversity in neuronal functions between different brain regions, are abnormal in schizophrenic patients. Such a disturbance may be the basis for the diversity of psychiatric symptoms in schizophrenics.