© 2022 Saudi Arabian Armed Forces Hospital. All rights reserved.Objectives: To compare the effect of pre-emptive erector spinae plane block)ESPB(applied before the procedure on opioid consumption during the procedure and analgesic demand and opioid consumption after the procedure. Methods: American Society of Anesthesiologists Physical Status Classification)ASA(I-II, 30 patients, with liver tumor and planned for microwave ablation)MWA(treatment were included in the interventional radiology clinic, Erciyes University, Kayseri, Turkey, Turkey between 2021 and 2022. Patients were randomized either to the ESPB or control group. Ultrasound-guided ESPB block with 20 mL of 0.25% bupivacaine was performed preoperatively in the ESPB group patients, and the patients who was not performed the ESPB the control group. All the patients were administered 1 μg/kg fentanyl, 1-2 mg/kg propofol, and 1 mg/kg ketamine for sedation during the MWA procedure after standard monitoring. Total opioid consumption and numeric rating scale)NRS(scores for pain were recorded at 0, 20, 40, and 60 minutes, and at 2, 4, 6, 12, and 24 hours after the procedure. Results: Total opioid consumption and total opioid amount during the procedure were statistically significantly lower in the ESPB group)p<0.001(. Although all of the patients in the control group needed additional fentanyl throughout the procedure, only 5 patients in the ESPB group needed additional fentanyl)p<0.001(. Post-procedure NRS score values were significantly lower in the ESPB group at 40 minutes, 60 minutes and 4 hours)p<0.05(. Numeric rating scale values at other times were statistically similar)p>0.05(Conclusion: This study showed that ESPB provided effective preemptive analgesia during MWA procedures.