The occurrence of epithelial tumors of the renal pelvis is rare in comparison with the frequent occurrence of other neoplasms involving the kidney. Joly1 in reviewing a collected series of 337 cases of tumor of the renal pelvis reported the occurrence of 120 benign papillomas, 138 papillary carcinomas, 29 transitional cell carcinomas and 50 squamous cell carcinomas. In analyzing individual cases it is difficult to classify the tumor accurately, because a varied terminology has been used, as is illustrated by the collected series of nonpapillary tumors of the renal pelvis which Kretschmer2 studied in 1917. I found that the following terminology had been employed by various authors cited in his collected series. Medullary carcinoma was used by 4 authors; scirrhous carcinoma by 2; pavement epithelium carcinoma by 3; alveolar carcinoma by 3; carcinomatous growth by 2; carcinomatous degeneration by 2; cancer by 3; pavement epithelioma by 9; encephaloid