Abstract Study objective: To evaluate and compare the analgesic effect of ultrasound-guided erector spinae plane (ESP) block with ultrasound-guided Quadratus Lumborum Block in pediatric lower abdominal surgeries. Design: Randomized, prospective, double-blinded trial. Setting: Operating room and surgical ward. Patients: Sixty patients, aged 1 to 7 years with ASA scores of I-II scheduled for elective lower abdominal surgery were included in the study. Interventions: Patients were randomized into two groups as ESPB group and QLB group. Ultrasound guided ESP block at L1 vertebral level was performed preoperatively using 0.5 ml/kg 0.25% bupivacaine (max 20 ml) to the patients in ESPB group. And ultrasound guided QLB block with transmuscular approach was performed preoperatively using 0.5 ml/kg 0.25% bupivacaine (max 20 ml) to the patients in QLB group. Measurements: Face, Legs, Activity, Cry and Consolability (FLACC) scores for pain were recorded at 0, 1, 3 and 6 h postoperatively. Analgesic requirements and time to first analgesic requirement were also recorded. Main results: Fifty-seven patients were included in the final analyses. No significant difference was determined between the groups’ FLACC scores at 0, 1, 3 or 6 h postoperatively (p > 0.05). No significant difference was also determined in times to first analgesia between the groups (p > 0.05). Conclusions: This study shows that the ESPB provides similar postoperative analgesia to the QLB in pediatric patients undergoing lower abdominal surgery. Clinicians could decide according to their clinical experiences. Clinical Trials: https://clinicaltrials.gov/ct2/show/NCT03463382. © 2019 Elsevier Inc.