Thoracic surgery in children is considered a highly invasive procedure that significantly affects respiratory mechanics and cardiovascular function, resulting in substantial physiological disturbances during the perioperative period. In pediatric patients, the chest wall is structurally immature and highly compliant; therefore, impairment of ventilation after thoracic surgery may persist and predispose to atelectasis, hypoxemia, and other pulmonary complications. Inadequate postoperative analgesia may further compromise respiratory function, delay mobilization, and prolong recovery, particularly during the first 48-72 hours after thoracic surgery, when pain intensity is typically greatest. Thoracic epidural analgesia (TEA) has long been regarded as the reference technique for postoperative pain control in thoracic surgery. However, in pediatric patients, epidural catheter placement may be technically challenging and is associated with potential adverse effects such as hypotension, bradycardia, urinary retention, and other neuraxial-related complications. Thoracic epidural blockade produces bilateral sympathetic inhibition, which may lead to hemodynamic instability, particularly during thoracic surgery requiring lateral decubitus positioning and one-lung ventilation. Furthermore, epidural placement is often performed after induction of general anesthesia in children, which may limit early recognition of neurological complications. These concerns highlight the need for alternative regional analgesic techniques that provide effective analgesia while maintaining hemodynamic stability. Ultrasound-guided erector spinae plane block (ESPB) has recently emerged as a promising fascial plane block for thoracic analgesia. Injection of local anesthetic deep to the erector spinae muscle and superficial to the transverse process allows cranio-caudal spread across multiple dermatomes, potentially providing analgesia to the posterior, lateral, and anterior thoracic walls. Increasing evidence suggests that ESPB offers effective perioperative analgesia in thoracic surgery with a favorable safety profile and minimal sympathetic blockade. Continuous ESPB catheter techniques have also been reported to provide sustained postoperative analgesia comparable to epidural analgesia. Despite these encouraging findings, direct comparisons between continuous ESPB and TEA in pediatric thoracic surgery remain limited, particularly regarding hemodynamic effects, adverse events, and technical feasibility. Therefore, this randomized controlled trial was conducted to compare the analgesic efficacy and hemodynamic stability of continuous ultrasound-guided thoracic ESPB with thoracic epidural analgesia in children undergoing thoracic surgery.