Gabapentin has demonstrated analgesic effects in clinical trials as a preemptive analgesic and in acute postoperative pain management. This study was conducted to evaluate whether the pre-emptive use of gabapentin could reduce postoperative pain and morphine consumption in patients after lower extremity orthopaedic surgery. Methods: 150 ASA I and II patients were randomly assigned to receive 900 mg gabapentin or placebo in a double-blind manner two hours before surgery under general anaesthesia. Postoperatively, the pain was assessed on a visual analogue scale (VAS) at 2, 4, 12, and 24 hours at rest. Morphine 0.05 mg/kg intravenously was used to treat postoperative pain on patients’ demand. Total morphine consumption in the first 24 hours after surgery was also recorded. Results: Patients in the gabapentin group had significantly lower VAS scores at all time intervals of 2, 4, 12, and 24 hours, than those in the placebo group (respectively, 55.50 [mean] +/- 15.80 [standard deviation], 57.30 +/- 19.30, 45.74 +/- 16.00, 44.60 +/- 17.64, versus 72.30 +/- 14.00, 70.50 +/- 18.13, 62.00 +/- 23.32, 66.50 +/- 25.70; p-value is less than 0.05). The total morphine consumed after surgery in the first 24 hours in the gabapentin group (15.43 +/- 2.54) was significantly less than in the placebo group (17.94 +/- 3.00; p-valueis less than 0.05). Conclusion: Pre-emptive use of gabapentin 900 mg orally significantly decreases postoperative pain and rescue analgesi