Our purpose in adding one more to the total of approximately fifty cases of primary ureteral tumor on record is to direct attention to a diagnostic finding which we believe to be unique and which may prove to be of clinical value in the preoperative diagnosis of this unusual and obscure condition. In this case it was possible to make a positive diagnosis while the ureteral wall was still intact, before the tumor had become larger than a pigeon's egg, before any changes in the kidney secondary to obstruction had taken place, without visible implants in the lower ureter or bladder, and without evidence of obstruction in the ureter to the passage of a catheter. To include a review of the literature with this brief report would mean mere useless duplication. Reports of cases including thorough reviews and complete bibliographies on this subject have been published during 1930 by McCown,