This randomized double-blind study was designed to determine whether administration of ketorolac either on schedule or as a component of patient-controlled analgesia (PCA) to patients who have undergone spinal stabilization would decrease PCA morphine use, decrease side effects, and/or enhance analgesia. Eighty inpatients undergoing spine stabilization by one surgeon were evaluated after excluding patients with contraindications to the use of ketorolac or morphine. All patients received PCA morphine. The patients were divided into four groups, which were given either intravenous saline (control group); intravenous ketorolac 15 mg every 6 hours; intravenous ketorolac 30 mg every 6 hours; or ketorolac added to the PCA morphine on a milligram per milligram basis. The outcome measures included pain scores. 24-hour morphine use, level of sedation, and side effect profile at six times during the first 24 postoperative hours. The total dose of morphine (P < .0001) and the cumulative doses for each of the six time periods (P varied between .02 and .0001 for the six time periods) were significantly higher in the control group than in the other three groups. There were no differences in doses administered by the other three groups. The pain scores were also significantly higher in the control group than in the other three groups, with no differences in pain scores among the other three. The sedation scores were higher (ie, patients more sedated) in the control group than in the other three groups at two of the six time periods (periods I and 6; P < .001). Ketorolac should be as a component of the PCA morphine in patients undergoing spine stabilization surgery. This results in decreased morphine consumption, decreased somnolence, and enhanced analgesia in comparison with patients who do not receive ketorolac.