Giant cell tumors of the jaw (GCTJ) are common in the long bones but rare in the craniofacial region, with only 1% of cases occurring in the latter; they account for approximately 3% to 5% of all primary bone tumors and 15% to 20% of all benign bone tumors. The biologic behavior of central giant cell lesions of the jaws ranges from quiescent to aggressive with destructive expansion, and the clinical behavior of GCTJ of the jaws is variable and difficult to predict. A number of tumors that occur in the jaws contain giant cells but are not true benign giant cell tumors. These include aneurysmal bone cyst, cherubism, simple bone cyst, osteoid osteoma, giant cell granuloma reparative, and tumor of hyperparathyroidism. This article reports a patient study of giant cell extended lesion in the left mandible from dental canine element to mandibular angle. The patient underwent excision of neoplasm and reconstruction of the mandible with an autologous bone graft of the iliac crest, but dentition was preserved over the resected area. No complications were detected, and 8 months postoperative control revealed excellent aesthetic and functional recuperation. This case is presented because of the following: (1) GCTJ is an infrequent tumor; (2) uncommon clinical presentation, severe deformity; (3) excessive size and jaw deformity; (4) fast growing; and (5) surgical treatment with preservation of the dentition in affected area.