The author has experienced a case of osteosarcoma arising from left maxilla. A 48-year old woman was admitted to Chunnam University Hospital on March 28, 1967 with chief complaints of purulent discharge from the oro-antral fistula, tenderness on the left upper molar region with slight tenderness and swelling of the left cheek for 5 months duration. X-ray study of the paranasal sinuses revealed destructive change principally involving the lateral wall and floor of the left maxillary sinus without significant productive change and the mass was encroaching in the cavity with considerable thickening of the mucous membrane on the roof and with slight hazziness in the left maxillary sinus. Histopathological examination revealed osteosarcoma. Partial maxillectomy and split thickness skin graft was performed on second hospital day and the patient was discharged with good condition on 28th postoperative day. There is no evidence of recurrence for 5 months after the surgery.