Background: Maxillofacial osteosarcoma (MOS) is a rare disease, mostly located to the mandible or maxilla. Surgical resection with wide free margins represents the key intervention to achieve favorable prognosis. MOS are particularly demanding to resect and surgically reconstruct because of the numerous tissue types and functions included in this location. Case reports: We introduce two patients with a highly malignant maxillary OS treated by primary tumor resection and immediate reconstruction with a microvascular soft tissue flap. After confirmation of relapse-free tissue healing and sufficiently free resection margins, osseous reconstruction was performed in a second operation by use of a virtually planned microvascular Fibula Flap. Both patients received implant-supported dental rehabilitation and show relapse-free for seven and three years, respectively. Conclusions: Combination of radical tumor resection, primary soft tissue reconstruction and secondary bone reconstruction allows high oncologic safety and optimal conditions for a thoroughly planned osseous as well as dental rehabilitation.