Fifteen years ago, general discussions on tumors of the brain were usual; today no such general discussion is of value. With the large series of cases of tumors of the brain that have been collected in neurosurgical clinics, a different type of study must be employed. To arrive at any satisfactory conclusions, one must consider special groups, either certain pathologic groups or lesions located in certain regions of the brain. In this article I shall consider the lesions of the frontal lobe and review my series of cases. Two years ago, I discussed this subject at a joint meeting, in London, of the British and American Neurological Societies. At that time I had twenty-five verified cases. During the past year and a half twenty more cases have been added. In these forty-five cases, all but one of the patients were operated on, with a mortality of 17 per cent.