Throughout the world the number of cases of renal pelvic and ureteral tumors has increased considerably during the last 2 decades. In Yugoslavia this increase has been exceptionally high since about 1953 or 1954. Many of our patients with these tumors come from regions where the population is affected by endemic nephropathy, the frequency of tumors in these regions being about 100 times higher than it is in other parts of Yugoslavia. In many cases these patients have renal failure and, therefore, conservative procedures are undertaken. Herein are reported the causes and results of therapy in 972 cases of renal pelvic and ureteral tumors collected in Yugoslavia. Particular attention has been paid to conservative operations (37 cases of renal pelvic and 64 cases of ureteral tumors), including their indications and possibilities. That many patients with renal pelvic and ureteral tumors have favorable conditions for a conservative procedure is confirmed by the comparatively good followup. However, in other cases a conservative operation is unreasonable and nephroureterectomy is mandatory.