The object of this communication is to suggest for consideration a therapeutic measure which I have found helpful in facilitating the removal of large malignant tumors of the kidney. I refer to the use of preoperative high voltage roentgen therapy for the purpose of reducing the size of these enormous neoplasms. Although I feel sure that this adjunct of therapy is being introduced in some clinics, the literature as yet contains no specific report of it. I cannot present a large series of cases, as, fortunately, a big renal tumor is not common. Also the effect that preoperative irradiation has on the chance of ultimate cure cannot be reported as this can be determined only with the passing of years. I shall, however, show the direct effect that irradiation has on the cytology and gross characteristics of these tumors and call attention to the immediate benefit of this treatment in