Background: ultrasound-guided quadratus Lumborumblock is performed as one of the perioperative pain management procedures for patients undergoing abdominal surgeries. Objective: the aim of this study was to compare the analgesic efficacy of ultrasound-guided trans-muscular quadratus lumborum block with transversus abdominis plane (TAP) block and intravenous opioid drugs during laparoscopic bariatric surgery and in the early postoperative period regarding pain relief, provision of comfort, early mobilization and improved respiratory functions. Patients and Methods: Setting and design: pilot exploratory study was conducted on 60 patients scheduled for elective laparoscopic bariatric surgeries. All patients received general anesthesia using IV fentanyl (1-2 μg/kg LBW). Group QLB (20 patients): received bilateral ultrasound-guided quadratus lumborum block after induction of general anesthesia using 0.2 ml/kg bupivacaine 0.125%. Group TAP (20 patients): received bilateral ultrasound-guided TAP block after induction of general anesthesia using 0.2 ml/kg bupivacaine 0.125%. Group GA (20 patients): received general anesthesia and then IV Morphine (0.1 mg/Kg LBW). Results: there was statistically significant difference between the three groups as regardsthe first call for rescue analgesia (morphine), total morphine consumption and pain scores; indicating that tansversus abdominis plane block was more effective than intravenous opioid drug analgesia, while quadratus lumborum block was more effective than tansversus abdominis plane block. Conclusion: this study concluded that quadratus lumborum block was the most effective technique in providing analgesia after laparoscopic bariatric surgery without associated hemodynamic instability in comparison to transversus abdominis plane block and intravenous opioid drugs.