To determine the effect of monitoring the Analgesia Nociception Index (ANI) on intraoperative opioid use, postoperative recovery, and analgesia in patients receiving preoperative bilateral erector spinae plane block (ESPB) for gynecological surgery under general anesthesia. Eighty patients classified in the American Society of Anesthesiologists physical status I-III scheduled for hysterectomy under general anesthesia were included in the study. After ultrasound-guided ESPB, patients were divided into 2 groups: control and ANI. In the control group, the intraoperative remifentanil infusion dose was adjusted using conventional methods; in the ANI group, the dose was adjusted according to ANI values of 50-70. Intraoperative remifentanil consumption, postoperative pain scores, additional analgesic requirements, and complications were recorded. Intraoperative remifentanil consumption was lower in the ANI group than in the control group (p < 0.001). Numerical rating scale (NRS) scores and requirements for additional analgesics in the postoperative recovery unit were both lower in the ANI group (p < 0.05). There were no significant differences between the groups in terms of nausea or vomiting in the recovery unit. ANI monitoring in patients undergoing gynecological surgery under general anesthesia with ESPB reduced opioid consumption during the intraoperative period. Intraoperative ANI monitoring enabled individualized opioid administration and guided determination of the required dose of analgesic agent. Trial registration This study was registered on ClinicalTrials.gov (NCT05106452, 22nd of October 2021).