Background Spinal surgery is associated with high incidence of severe postoperative pain difficult to easy control. Appropriate treatment modalities decreased the postoperative morbidity, increased patient satisfaction, allowed early mobility, and decreased hospital costs. Lidocaine was used as intravenous additives to control intraoperative pain and decrease postoperative pain. As lidocaine, dexmedetomidine infusion associated with lower postoperative pain scores decreased the opioid consumption and its related adverse events. The aim of this double blind randomized prospective comparative study was to compare the efficacy of intraoperative dexmedetomidine versus lidocaine infusion on hemodynamics, fentanyl requirements, and postoperative analgesia among 66 patients subjected to lumbar fixation surgery and randomized into group D which received dexmedetomidine 1 μg/kg infusion over 10 min as a loading dose then 0.3–0.5 μg/kg/h after induction of anesthesia as maintenance dose and group X which received lidocaine 0.3–0.5 mg/kg/h after induction of anesthesia. Results At 10, 15, 30, and 60 min, the mean arterial blood pressure and heart rate significantly decreased in group D compared to group X, and there was significantly higher total dose of intraoperative analgesic for fentanyl in group X than group D. There was significantly higher numeric rating scale in group X compared to group D at 2, 4, 6, 9, 12, 18, and 24 h postoperative with significant early request of the first analgesia, higher incidence of analgesic needs, and higher dose of postoperative analgesia paracetamol, voltaren, or pethidine in group X compared to group D. Conclusions The intraoperative use of dexmedetomidine IV infusion was an alternative mode to decrease the demands of analgesia following spine surgery.