Abstract
A case of carcinoma in situ of the renal pelvis, diagnosed by exfoliative cytology from ureteral specimens and treated by nephroureterectomy, is reported. Urothelial carcinomas in situ are very rare in the renal pelvis, but an increasing number in the bladder have been diagnosed. Urinary cytology plays the most important role in the diagnosis of carcinoma in situ of the renal pelvis and may be used as a screening test of patients exposed to known carcinogens.