BACKGROUND Although vascularized bone grafts have become well accepted in adults, especially following ablative head and neck procedures, there are few long-term reports of their use in pediatric patients. METHODS In this study, the authors analyzed the outcomes of 18 free fibula grafts in 16 patients aged 10 months to 21 years (mean, 12 years) with an average follow-up of 5 years. Eleven patients had cancer-related defects, four had craniofacial anomalies, and one had a posttraumatic deformity. All patients with congenital malformations had been followed since birth, and the others had been followed from the time of their original cancer diagnosis or injury. RESULTS Of the 16 patients, seven underwent irradiation and seven underwent chemotherapy. The most severe deformities were seen in those with cancer resection and radiation therapy. Most defects were hemimandibular; there was one total mandibular defect (a child with Ewing sarcoma). Ten patients had had previous failed nonvascularized bone grafts. Eleven flaps were osteocutaneous with either intraoral or extraoral components; most had multisegmental osteotomy and had one arterial and two venous anastomoses. All free fibula transfers were successful; there were no vascular problems and only two minor complications. CONCLUSIONS A number of lessons are learned from careful analysis of this unique group of patients, and an algorithm of pediatric mandibular reconstruction is proposed.