Male Macaca mulatta monkeys were studied with slow application of axial forces to the vertebral column with forces which produced an approximate 50% reduction in the afferent or efferent evoked potential amplitude. Autoradiographic studies with 14C deoxyglucose demonstrated a marked reduction in metabolic activity at the cervical-medullary junction and cervical spinal column while other levels of the spinal column were essentially normal. Examination of the neural tissue with light microscopy was unremarkable. However, in a 7-day survival monkey, damage was observed in the central gray nervous tissue at the cervical level. Electron microscopy studies with similar force application demonstrated shrinkage of the axoplasm and disruption of the myelin lamellae in the upper and lower cervical regions while brain and thoracic spinal cord tissues were minimally altered. These preliminary findings suggest that the greatest effects occur in the cervical regions with axial distension and that 14C deoxyglucose and electron microscopy may be valuable for the evaluation of early physiologic alterations following biomechanical trauma to the brain and spinal column.