The aim of this study was to compare the analgesic effect of patient-controlled morphine with that of patient-controlled morphine plus dexmedetomidine on postoperative pain in patients undergoing laminectomy. Ethics committee of the institute approved this study, and after a written informed consent obtained from each participant, 64 patients with American Society of Anesthesiologist physical status I and II, scheduled for laminectomy were recruited for this prospective, randomized controlled study. A standardized load morphine dose of 0.15 mg/kg was given to all patients. Patients were randomized into 2 groups postoperatively. The settings were IV morphine, bolus dose 0.02 mg/kg, with a lock out time of 15 minutes in group morphine (n=32). The settings were bolus dose 0.02 mg/kg and 0.1 μg/kg dexmedetomidine with a lock out time of 15 minutes in group morphine plus dexmedetomidine (n=32). Hemodynamic variables, pain scores, and sedation scores were recorded postoperatively. No differences were detected in the demographic data, hemodynamic variables, and pain scores. Total morphine consumption was 46.37±12.05 mg in group morphine and 16.03±8.55 mg in group morphine plus dexmedetomidine. Sedation scores were significantly higher in group morphine plus dexmedetomidine after the first hour. Using morphine or morphine plus dexmedetomidine in patient-controlled analgesia provided effective postoperative analgesia. In the morphine plus dexmedetomidine group, postoperative morphine consumption was lesser than that of the group with only morphine. This result may be explained as a synergistic effect of dexmedetomidine with the analgesic action of morphine.