<p class="abstract">Osteosarcoma is the most common primary malignant bone tumor. Jaw is an uncommon site. The etiopathogenesis is still unknown. We present a case of 47-year-old female who underwent left partial maxillectomy as the lesion increased in size over one month after removal of a tooth. Prior to the surgery, computed tomography (CT) scan was suggestive of left maxillary sinus carcinoma and biopsy report was suggestive of spindle cell lesion. Partial maxillectomy specimen received in which size of the tumor was 5.5×5.5×4 cm with a pearly-white, solid, homogenous cut surface with gritty sensation on cutting. On histopathology it turned out to be osteosarcoma of the jaw. Mouse double minute 2 homolog (MDM2) and special AT-rich sequence-binding protein 2 (SATB2) was done to confirm the diagnosis of osteosarcoma. The patient was given chemotherapy after the confirmation and at present the patient is doing well.</p>