Until now, there have been no reliable serum markers for monitoring urothelial cancers. However, it has been reported that it is possible to detect circulating urothelial cancer cells using the CellSearch Circulating Tumor Cell (CCTC) Test (Immunicon, Huntingdon Valley, PA). This case report is a representative example of the good correlation between the change of the number of circulating tumor cells in the blood and the state of an urothelial cancer after therapies. Detection of circulating tumor cells might be a valuable serum marker for urothelial cancer patients with distant metastasis.