As scoliosis surgery in children is a large invasive surgery, postoperative pain control is difficult. We examined the difference of the analgesic effect between patients with and without DEX administration using the intravenous patient controlled analgesia (IV-PCA) of fentanyl after the scoliosis surgery in 18 patients. The frequency of PCA bolus administration in the period with DEX administration was significantly less compared with the period without DEX. There were no effects on circulatory condition and level of consciousness in all patients during DEX administration. And the starting times for drinking water and oral feeding were prolonged in a patients receiving a large amount of continuous fentanyl infusion. It is highly probable that effects of fentanyl such as inhibition of gastrointestinal motility and nausea and/or vomiting are contributory. The amount of fentanyl required for postoperative analgesia was decreased by combining DEX. In addition, it is thought that side effects of fentanyl are reduced in low dose fentanyl administration cases. As a result, it may bring early postoperative recovery. The IV-PCA using fentanyl with DEX may be useful for postoperative analgesia in scoliosis surgery. We will recommend using DEX (0.25 microg x kg(-1) x hr(-1)) together with fentanyl (0.5 microg x kg(-1) x hr(-1)) for this purpose.