Sixty patients with lumbar spine conditions were randomized to receive either a modified thoracolumbar interfascial plane (mTLIP) block (n=30) or an erector spinae plane (ESP) block (n=30). The primary outcome of interest was 48-hour postoperative fentanyl consumption. Secondary outcomes included additional intraoperative fentanyl requirements, postoperative pain scores at rest at various time points (1, 2, 4, 6, 12, 24, and 48 hours), and incidence of nausea, vomiting, and excessive sedation. Outcomes were assessed up to 48 hours postoperatively. Overall, the results of the study revealed that the ESP block was associated with lower 48-hour postoperative fentanyl consumption and lower postoperative pain scores compared to the mTLIP block, particularly within the first 24 hours postoperatively. The findings suggest that the ESP block may be more effective for pain management in lumbar spine surgeries than the mTLIP block.