Paraplegia resulting from the operative treatment of scoliosis is a serious complication feared most by orthopedic surgerns. Scoliosis Research Society reported the incidence of acute neurological complications resulting from the treatment of scoliosis as 0.72% in 1975. Thus, the importance of the development of some form of adequate practical spinal cord monitoring during major corrective surgery of the spine has become increasingly recognized as the surgery in this area has accelerated. In order to reduce the incidence of such neurological complications, intraoperative spinal cord monitoring has introduced since nineteen seventies. Monitoring of cortical somatosensory evoked potentials (CSEP) were applied in surgery of 31 cases of scoliosis and 4 cases of cervical spine lesions at Department of Orthopedic Surgery at Seoul National University Hospital, from Jan. 1982 to May 1985, and the following results were obtained. 1) Quantitative analysis of CSEP was done in 31 cases of scoliosis as grouping into preincision, preinstrumentation, postinstrumentation and skin closure periods. From preincision period, P1 and N1 latencies prolonged significantly across all periods but not from preinstrumentation period to subsequent periods. P1-N1 amplitude and P2-N2 amplitude were decreased significantly between preincision period and other periods but no significant change was noted from preinstrumentation period to skin closure period. (P<0.05) 2) Abnormal CSEP findings were noted during operations in 4 cases, in which acute neurological complications were prevented with CSEP monitoring. 3) We experienced a case in which CSEP was abolished on the concave side of the curve while CSEP was normal on the convex side, during distraction. So it is considered that the ankle electrode should be placed on the concave side of scoliosis to detect neurological complication. 4) Correctibility of deformity in scoliosis surgery was increased from 44.1% to 51.3% with the use of intraoperative CSEP monitoring without acute meurological complications. 5) CSEP monitoring during spine surgery is an effective method to prevent neurological complication.