© 2015 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Radiotherapy for oral cancer that has caused jaw absorption has been reported occasionally to result in bone regeneration, but this regeneration is generally partial. We report a case of marked bone production from the mandibular head to the reconstructed fibula after chemoradiotherapy for the recurrent tumor. A 50-year-old man had undergone upper neck dissection, mandibular segmental resection and reconstruction using a free vascularized fibula osteocutaneous flap for a primary intraosseous squamous cell carcinoma in the right mandible. Six months later, CT showed tumor recurrence with bone destruction from the mandibular head to the reconstructed fibula. He received chemoradiotherapy, consisting of radiotherapy (70Gy in 28 fractions) with docetaxel (10mg/m<sup>2</sup> once weekly for 6 weeks) and cisplatin (4mg/m<sup>2</sup> daily for 28 days). Marked bone regeneration was observed, with the mandibular head and fibula almost completely recovering from bone destruction. At present, 7 years later, there has been no sign of tumor recurrence.