Children, like adults, are at risk for neurological injury during a variety of surgical procedures. Intraoperative electrophysiological monitoring (IOM) provides information about the functional integrity of the nervous system during surgery. This information may determine the mechanism of injury and prevent damage by identifying nerves and detecting dysfunction at a reversible stage. Electrophysiological techniques may also help direct therapy by improving injury localization, detect the presence or absence of axonal integrity in peripheral nerve lesions, and identify rootlets with the greatest contribution to spasticity in patients undergoing selective dorsal rhizotomy (SDR). Electrophysiological techniques used are modified from those employed in the diagnostic laboratory. The first portion of this article reviews IOM experience at the Mayo Clinic in patients under 18 years of age from 1985 to 1991. The types of procedures monitored, the monitoring modalities used, technical problems unique to children, and neurological outcome are discussed. Subsequently presented are the application and techniques of electrophysiological monitoring during SDR as currently practiced at the University of Kentucky and other medical centers.