Erector spinae plane block (ESP) is a regional anesthesia technique consisting of blocking the interfascial plane, where local anesthetic (LA) is injected at the site where the dorsal branch of the spinal nerve emerges. There are various publications on the application of the block (EPS) in the adult population, however there are few reports of the use of this block in pediatric surgery. We present the first case report of an infant under 9 months of age with the presence of a tumor in the anterior mediastinum, who underwent a resection through the 6th intercostal space, previous blockage of the erector spinae under ultrasound vision. The patient did not present adverse effects and was discharged on the fourth postoperative day.