Background: The article dealt with evaluating the efficacy of bilateral single shot ultrasound-guided (US guided) lumbar erector spinae plane block (ESPB) in patients scheduled for L3-L5 posterior lumbar interbody fusion (PLIF) under general anaesthesia (GA). The primary goal of the article was to determine total morphine consumption 24 hours postoperative. Secondary goals included determining total intraoperative and postoperative opioid consumption, length of post-anaesthesia care unit (PACU) stay, and complications. Methods: Sixty patients, American Society of Anesthesiologists (ASA) I and II, aged 18–60 years, undergoing PLIF under GA were enrolled in this prospective, randomised, double-blinded study. Patients were randomised to 2 groups (30 patients each). Group I (control group) received GA only and group II received preoperative bilateral ESPB with 20 ml 0.25% bupivacaine. The primary outcome was postoperative morphine consumption. Secondary measurements were intraoperative fentanyl consumption, time to first analgesic request, static and dynamic visual analogue score (VAS), haemodynamic changes, PACU stay, and complications. Results: Patients who received ESPB showed a significant decrease in intraoperative and postoperative opioid consumption, shortened PACU stay, and haemodynamic stability compared to those who received GA only. Significant increase of VAS was observed in group I compared with group II up to 8 and 12 hours postoperative (static and dynamic VAS respectively). Conclusion: Preoperative bilateral single shot US-guided ESPB provided safe and effective postoperative analgesia for PLIF with reduced opioid consumption and short PACU stay.