The purpose of this article is to describe a case of an 8-month-old girl who was diagnosed with a melanotic neuroectodermal tumor and was submitted to a right hemimandibulectomy and immediate reconstruction with a fibular osteocutaneous free flap. At 12-year follow-up, the longest reported in a patient this young, the transferred bone had grown much like the native mandible, and the patient had adequate mandibular contour and function. No revisions were needed, although orthopedic surgery was performed to correct an ankle valgus deviation on the donor leg. It is the opinion of the authors that microsurgical mandible reconstruction in very young patients is efficient and that the surrounding structures contribute to the remodeling of the bone segment to achieve characteristics similar to those of the native mandible. © 2013 Wiley Periodicals, Inc. Microsurgery 34:51–53, 2014.