Summary:The delineation of neuropathology possibly responsible for the neurobehavioral deficits following closed head injury has been a hurdle. Although computerized tomography (CT) and magnetic resonance imaging (MRI) scans have proved invaluable in this regard, both of these techniques are limited in that they provide a static perspective of neural structure. Perhaps for this reason, neuropsychological evaluation, providing a more dynamic perspective of brain function, occasionally presents evidence of impaired neurobehavioral functioning when CT and MRI scans show no evidence of neuropathology. We present neuropsychological and positron emission tomography (PET) scan data on six head injury cases. In each case, CT and/or MRI scans yielded no or little evidence of neuropathology. PET scans, however, corroborated impaired brain function detected by neuropsychological testing. These findings indicate that PET scanning and neuropsychological testing have the potential to play an important role in the description of neurobehavioral deficits after head injury.