Osteosarcoma is a malignant neoplasm of the bone, commonly affecting the long bones. The involvement of the jaws is rarely noticed. This neoplasm often shows a typical clinical behavior as well as varied radiological appearances. To confirm the final diagnosis of an osteosarcoma, it is often required to carry out a histopathological examination of the multiple biopsy specimens. Moreover, a vigorous discussion amongst experts is as well required. In light of their aggressive behavior, an early diagnosis is crucial to determine the adequate treatment. Dental professionals may be the first to detect jaw osteosarcomas in their initial stages. This article presents a case of maxillary osteosarcoma in a 45-year-old male patient with important evolution due to delayed diagnosis. It also highlights the importance of CT scan and MRI in the control of tumor progression and in the choice of the adequate treatment.