Cotrel-Dubousset instrumentation has been a major advance in spinal surgery but, at least theoretically, it carries a higher risk of spinal cord damage. This paper describes our experience in monitoring the function of either ascending sensory pathways or both ascending sensory and descending motor pathways in the spinal cord during such procedures. Seventy-nine juvenile and adult patients are presented in whom either somatosensory recording (n = 39) or simultaneous corticospinal and somatosensory monitoring (n = 40) was attempted by means of epidural electrodes during corrective surgery with Cotrel-Dubousset instrumentation. Abnormal evoked responses were seen in two cases but these resolved in both before the operation was completed. No new neurological deficits occurred nor were any pre-existing deficits increased.