In this randomized-controlled study, we investigated the effects of combined administration of pregabalin and dexamethasone on postoperative pain and analgesic requirements, and functional outcome in patients who underwent lumbar spinal surgery.One hundred eight patients were randomized to group C (placebo+placebo), group P (pregabalin + placebo), or group PD (pregabalin+dexamethasone). According to their allocated group, patients received placebo or pregabalin 150 mg every 12 hours starting 1 hour before anesthetic induction for a total of 8 doses. Dexamethasone 16 mg or normal saline was injected before the induction of anesthesia. The pain intensity, analgesic requirements, and side effects were assessed in the postoperative period: postanesthesia care unit, 12, 24, 48, and 72 hours. Pain intensity and daily activity performance were also assessed 1, 3, and 6 months after surgery.Compared with group C, the pain scores were lower in group PD at 24 hours after surgery (P = 0.011). The frequency of additional rescue analgesic administration was significantly lower in group PD until 48 hours after surgery (P < 0.05) and in group P at 24 to 48 hours (P = 0.005) relative to group C. Back pain intensity at work was lower (P = 0.048) and daily activity performance was better (P = 0.006) in group PD compared with group C at 1 month after surgery.Combined administration of pregabalin and dexamethasone conferred analgesic benefits superior to those of pregabalin alone. This regimen also helped facilitate return to normal daily activity after surgery.