A 47-year-old woman who was diagnosed with right pyelonephritis by a local physician, but failed to respond to antimicrobial chemotherapy, was referred to our hospital. Here, the diagnosis of right pyonephrosis was confirmed byabdominal computed tomography(CT). Retrograde pyelography(RP) revealed a severe stricture at the ureteropelvic junction, and it was considered difficult to advance a guidewire through the stricture. Urine cytologywas pseudo-positive ; thus, the possibilityof a malignant tumor of the urinarytract could not be ruled out. Therefore, right nephroureterectomywas performed. The final, histopathological diagnosis was urothelial carcinoma, (G2, pT3). After surgery, the signs and symptoms of the infection were rapidlyameliorated ; however, swelling of the lymph-nodes between the aorta and vena cava was observed, which was considered to be metastasis. Therefore, 4 courses of gemcitabine ＋cisplatin therapywere administered, which resulted in complete resolution of the lymph-node swelling. The patient has remained free of recurrence for 2 years after surgery.