In any review of late results following nephrectomy for malignant tumors of the kidney, the particular type of neoplasm which has been removed should be considered. Although adenocarcinoma (also termed "hypernephroma") is by far the most common malignant growth which occurs in the kidney, epithelioma of the renal pelvis, sarcoma and Wilms' tumor are not infrequently encountered. The clinical course, age of the patient, pathologic characteristics, indications for treatment and prognosis are some of the pertinent features which vary widely depending on the histologic nature of the growth. With the primary purpose of determining late results, the records of 642 cases in which operations were performed for malignant tumors of the kidney at the Mayo Clinic in the years 1910 to 1936 inclusive have been reviewed. Nephrectomy was performed in 568 cases and in the remaining seventy-four cases an exploratory operation revealed an inoperable lesion. The operations were performed by