Objectives We designed a clinical study to determine: a) the safety and efficacy of patient-controlled analgesia (PCA) therapy in children and adolescents undergoing major-operations, b) if the use of a concurrent opioid infusion improved the efficacy of conventional PCA therapy, and c) if nurse control of the PCA device was a useful alternative in the intensive care unit (ICU) setting. Design Subjects were randomly assigned to receive morphine sulfate for postoperative pain relief via intermittent PCA boluses on demand or PCA plus a continuous infusion (PCA + CI). Children (n = 12) who were unable to use the PCA device because of inadequate developmental level or upper extremity weakness were assigned to a nurse-controlled analgesia (NCA) group. Setting In the ICU of a university-based pediatric teaching hospital. Patients Fifty-four children and adolescents underwent elective scoliosis surgery. Interventions The PCA devices were connected to the patient's i.v. catheter immediately after surgery. Morphine sulfate was administered on demand by either the patient or an ICU nurse for pain relief during the first 72 h after the operation. Main Outcome Measures Pain scores were recorded simultaneously by both the nurse and the patient using standardized visual analog scales. Opioid analgesic usage, side effects, and therapeutic interventions were recorded by the ICU nurse. Results There were no differences between the PCA and PCA + CI groups with regard to morphine use, pain relief, side effects, or patient satisfaction. Nurses consistently underestimated their patient's level of pain, and children in the NCA groups received less morphine per kilogram than those who self-administered their own analgesic medication. Conclusions Both PCA and NCA were safe and efficient methods of analgesic administration in the pediatric ICU setting. However, use of a concurrent opioid infusion with PCA therapy did not provide any clinically significant advantages over intermittent bolus doses of the analgesic medication after scoliosis surgery. For patients unable to use a conventional PCA device, NCA is an acceptable alternative for the management of acute pain in the ICU setting.