Osteosarcoma of the jawbones is a rare malignant mesenchymal neoplasm with the tendency for new bone being directly formed by the tumor cells. Clinically, the tumor may be central or peripheral--periosteal--and histologically can be divided into three subtypes: osteoblastic, fibroblastic, and chondroblastic. This report presents a case of a central osteoblastic osteosarcoma of the left maxillary tuberosity and maxillary sinus. Problems related to definitive diagnosis and therapy are described and discussed.