The need for reconstruction of large bone, soft tissue defect of mandible has greater emphasis due to development of industry, traumatic accident and increase of tumor. The mandibular reconstruction had greatly progressed through the first and the second World Wars. The Fibular free flap by using microscope was reported in 1970 and many maxillofacial reconstructive surgeons had used. In 1988, Dr. Hidalgo first reported mandibular reconstruction by using fibular free flap. Mandibular reconstruction by using fibular free flap has several advantages. First, it provides up to 25 cm of bone, enough to reconstruct any length of mandible defect. Second, a skin island, based on a septocutaneous blood supply, is available in a size large enough to simultaneously reconstruct internal and external soft tissue defect. Third, The fibular donor site morbidity is low, fourth, it provides a esthetic effect of mandible line. And finally bone viability is good. The Fibular osteocutaneous free flap was performed after COMMANDO operation due to squamous cell cancer in oral cavity (15 cases). Therefore we report out successful operation of the mandible reconstruction by using fibular osteocutaneous free flap.