Positron emission tomography with oxygen-15 was used to compare regional cerebral blood flow and the regional cerebral metabolic rate of oxygen in a group of predominantly never-treated, acute schizophrenic patients and in matched controls. The results of this study did not support the hypothesis that schizophrenics have reduced frontal blood flow and/or metabolism; and only equivocal support was obtained for the hypothesis that metabolism within the basal ganglia is reduced in schizophrenics. However, support was obtained for the hypothesis that an abnormality in hemisphere laterality may underlie schizophrenic illness.