OBJECTIVESPain management is an important issue following lumbar spinal surgery. Wound infiltration is a technique that a local anesthetic solution is infiltrated into the tissues around the surgical area. Previous studies reported that US-guided modified thoracolumbar interfacial plane (mTLIP) block after lumbar spinal surgery provided effective analgesia. In this study, we aimed to compare the analgesic efficacy of the US-guided mTLIP block and wound infiltration following lumbar disc surgery. METHODS60 patients aged 18-65 years, ASA classification I-II, and scheduled for lumbar disc surgery under general anesthesia were included in the study. US-guided mTLIP block was performed via the lateral approach in group T (n=30), and wound infiltration was performed in group W (n=30). Opioid consumption, postoperative pain scores and adverse effects of opioids, such as allergic reactions, nausea, and vomiting, were recorded. RESULTSOpioid consumption and the use of rescue analgesia were significantly lower in group T in all the postoperative periods (1, 2, 4, 8, 16, and 24 h) (p<0.05). The VAS scores for pain during mobility and while at rest were significantly lower in group T than those in group W 8 h after the surgery (p<0.05). The incidences of nausea, vomiting, and itching in group W were higher than the incidences in group T. CONCLUSIONThe mTLIP block provides effective analgesia for the first 24 h following lumbar disc surgery, and it may be an alternative to wound infiltration for pain management.