78 patients, <18 years of age, diagnosed with idiopathic scoliosis and scheduled to receive posterior spinal fusion and instrumentation, were randomly assigned into 1 of 2 groups to discern the effect a combination of intravenous magnesium and ketamine had on morphine consumption during and after scoliosis surgery, when compared to the administration of ketamine alone. Patients received intervention with both ketamine and magnesium or with ketamine alone. The results of the study indicated that average consumption of morphine was significantly lower in patients who received treatment with ketamine and morphine when compared to those who received ketamine alone (at 4, 8, 12, 18,30, 36 and 48 hours). VAS scores did not significantly differ between groups. Sleep quality for patients in the ketamine and morphine treatment group was significantly better on the first postoperative night when compared to those in the ketamine alone group, but this difference did not exist after the second postoperative night.