BACKGROUND Intravenous lidocaine infusion is known to reduce postoperative pain for days or weeks beyond the infusion time, and plasma half-life in several types of surgical procedures. OBJECTIVE To evaluate the effect of intravenous (IV) lidocaine infusion on long term postoperative pain intensity for 3 months in patients undergoing spinal fusion surgery. METHODS Prospective randomized, double-blinded study. METHODS Assiut University Hospital, Assiut, Egypt. METHODS Forty patients undergoing spinal fusion surgery were randomized into 2 equal groups (n = 20 in each). Patients in the lidocaine group received IV lidocaine at a dosage of 2.0 mg/kg slowly before induction of anesthesia, followed by lidocaine IV infusion at a rate of 3.0 mg/kg/h until the end of surgery. Patients in the control group received an equal volume of normal saline. The following data were assessed: pain by Visual Analog Score (VAS) at 1 hour, 6 hours, 12 hours, 24 hours, 48 hours, at discharge time, and at 1 month, 2 months, and 3 months post-operation, time to first request for additional analgesia, and total morphine consumption in 24 hours. RESULTS Lidocaine significantly reduced the postoperative pain score (VAS) for up to 3 months (P < .05), and significantly reduced morphine consumption (4.5 mg vs. 19.85 mg) in the 1st 24 hours postoperative. Lidocaine also significantly, prolonged (P < .05) the time to first request for additional analgesia (9.56 ± 2.06 hours vs 1.82 ± 0.91 hours). CONCLUSIONS Intra-operative lidocaine, when given intravenously as a bolus followed by an infusion, significantly decreased long term postoperative back pain intensity in patients undergoing spinal fusion surgery.