Osteosarcoma (OS) is a malignant mesenchymal tumor, which rarely occurs in the maxilla. Although variable histologic and radiographic features of OS have been reported previously, in the majority of the cases painful swelling of the jaw is mentioned as the first clinical presentation. Furthermore, early diagnosis and wide surgical resection of the tumor are the most important determinant factors of prognosis. Therefore, the unusual clinical presentations of OS should be considered meticulously to expedite the diagnosis process. We describe a case of OS of the maxilla with extremely unusual presenta-tion in a 42-year-old female, that was initially designated as "epulis fissuratum". Here, we highlight the importance of com-bining the clinical, radiographic and histopathologic examination to obtain a definitive diagnosis and also the significance ofearly effective surgical intervention in evaluation of pathologic lesions.