WHILE much work has been devoted to tumors of the ethmoidomaxillary area, primary tumors of the frontal bone, including the frontal sinus, have attracted the attention of the investigators to a less degree. The reason is that tumors of the frontal bone, as a whole, particularly those originating in the frontal sinus, do not occur as frequently as tumors of the ethmoidomaxillary area. Grégoire and Martin1 collected, in 1948, from the literature 31 cases of primary carcinoma and 25 cases of sarcoma of the frontal sinuses. The question arises as to the cause of the difference in the frequency. This question, which is related to the fundamental question of the origin of the tumors as a whole, cannot be answered. However, a few factors can be determined to explain the difference. In the texbooks great emphasis is laid upon the exposure of the superior maxilla to various traumatisms due