Chondroblastic osteosarcoma is a rare and milignant disease. A hard and painless mass was found at the right side of the maxilla of a 14 years old girl. The biopsy proved to be a chondroblastic osteosarcoma. Partial maxillectomy from right upper central incisor to 2nd molar was performed. There haven't any evidence of recurrence following 10 years postopertively.