The odontogenic myxoma is a relatively rare, benign tumor that occurs on the jaw. A 41 year-old man visited Seoul National University Dental Hospital because of swelling of the mandible. Clinical and radiographic evaluation showed a huge mass invading most of the mandible. After biopsy, he was diagnosed with odontogenic myxoma. For resection of the lesion, partial mandibulectomy and reconstruction with a vascularized fibular free flap was done. The result showed successful removal of the lesion. Reconstruction resulted in satisfactory functional and esthetic outcomes. We conclude that huge benign neoplasms such as odontogenic myxomas can be successfully treated by using a wide margin of resection followed by vascularized fibular free flap reconstruction.