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. CONCLUSION: A number of lessons are learned from careful analysis of this unique group of patients, and an algorithm of pediatric mandibular reconstruction is proposed.