We report a case of granulocyte-colony stimulating factor (G-CSF) producing infiltrating urothelial carcinoma of the left renal pelvis. The patient was referred to our hospital for fever and anorexia. Blood tests showed elevated level of leukocytosis without any infectious diseases. The serum concentration of G-CSF was remarkably elevated. Abdominal computed tomography (CT) revealed a huge mass in the left renal pelvis and para-aortic lymph node enlargement. He was underwent left nephroureterectomy and para-aortic lymphadenectomy. The histological examination revealed infiltrating urothelial carcinoma with positive staining for G-CSF antibody. The postoperative course was smooth and the leukocyte count became normalized within a week postoperatively. However, multiple lung metastasis and leukocytosis were revealed about 2 months after the operation. G-CSF producing infiltrating urothelial carcinoma of the renal pelvis is reported to have a significantly poor prognosis, so it is very important to monitor closely after the operation.