Obesity is a complex chronic disease that has become a major public health concern worldwide, with the prevalence of obesity increasing dramatically over the past few decades. Patients with morbid obesity pose a challenge for perioperative pain management. High ceiling analgesics-opioids have limited role due to safety concerns for patients with or without obstructive sleep apnea . Insufficient postoperative pain management can have negative effects on recovery and quality of life, as well as limit patient comfort and delay the patient's ability to return to work after surgery . Due to the numerous negative side effects of opioid drugs, including physical dependence, nausea, vomiting, and respiratory depression and subsequent airway obstruction, the Enhanced Recovery after Surgery (ERAS) guidelines for bariatric surgery currently advise opioid reduction in this procedure. Ultrasound-guided erector spinae plane block (ESPB) and modified thoracoabdominal nerve block (M-TAPA) are both regional anesthesia techniques used to provide perioperative analgesia for obese patients undergoing LSG . The ESPB targets the spinal nerves as they exit the erector spinae muscle, providing analgesia to the abdominal wall and paraspinal muscles. The technique has shown promising results in various surgical procedures and has a low risk of complications. By blocking the spinal nerves, the ESPB can provide effective pain relief in the postoperative period for patients undergoing LSG . On the other hand, the M-TAPA targets the thoracic intercostal nerves and the abdominal wall, providing analgesia to these areas. The technique has been shown to provide effective perioperative analgesia in patients undergoing LSG. With or without ultrasound guidance, the use of M-TAPA can provide effective pain relief and reduce the need for opioid medication in the postoperative period. This study aimed to compare the analgesic effect of ultrasound guided modified thoracoabdominal nerve block and an erector spinae plain block in patients undergoing LGS