The author analyzed the clinical and radiographic findings of 109 malignant tumors of epithelial origin occured in the jaws of the patients visited the infirmaries of Dentistry, Chosun University and several university in Korea during 1978 to 1988. The observed results were as follows: 1. It appeared that 93 % of the total 397 cases diagnosed as oral malignant tumors were squamous cell carcinomas. 2. The incidence ratios between nodular type and ulcer type were 4 to 1 in maxilla and 3 to 1 in mandible. 3. In nearly 50% of all patients complained of pain due to impingement of tumor mass or ulcer. 4. Most of carcinomas of maxilla eventually invaded into maxillary sinus and palate. 5. Characteristic features on the radiographs were the lesion with ill-defined border, the direct destruction of the alveolar bone and anatomical landmark without displacement of the involved teeth and the gray shadow of the tumor mass in the lesion.