Mild-moderate closed head injury (CHI) can be followed by neuropsychological impairments in recent memory and attention, despite the absence of discernible structural abnormalities in a significant number of patients. To determine whether CHI may result in cerebral glucose metabolic abnormalities, we used fluorodeoxyglucose (FDG) technique with PET imaging to measure local cerebral metabolic rates for glucose (LCMRGlu) in three CHI patients and three matched normal controls. The CHI patients were between 3-12 months post-injury. All had deficits in attention and recent memory shown by neuropsychological testing. CT, MRI, EEG and drug screens were negative at the time of PET scanning. Subjects were engaged in a vigilance task throughout the initial 30 min following FDG administration. Group comparisons were made using t tests. There were no significant group differences found in global glucose metabolic rate. Nevertheless, the CHI group exhibited significantly decreased LCMRGLu in medial temporal, posterior temporal, and posterior frontal cortices, as well as in the left caudate nucleus. LCMRGlu was significantly increased, relative to controls, in anterior temporal and anterior frontal cortices. These results suggest that CHI patients can have regional glucose metabolic abnormalities, indicative of altered neuronal function, despite the absence of discernible anatomic abnormalities.