We report 12 cases of osteosarcoma (10 located in the mandible and 2 in the maxilla). There were 8 men and 4 women who were older than usually observed in osteosarcoma at other sites (8 of 121 patients were over 30 and the average age was 34 years). Clinical signs were variable. Bone tumefaction was the most frequent sign, with a diameter greater than 5 cm in most cases (10 out of 12). Surgery alone was used for 8 patients and radiosurgery for 3. Follow-up is available for 8 patients. All presented local recurrence with extensive tumors progression. All died within an interval of 3 to 30 months despite palliative surgery and/or radiotherapy or chemotherapy.