Infiltrating urothelial carcinoma sarcomatoid variant is a rare variant of urothelial carcinoma. We report a case of a 68-year-old female with a history of hematuria. CT scan with contrast showed a mass in the 1/3 distal of the right ureter. The biopsy result showed a high-grade infiltrating urothelial carcinoma. A radical nephroureterectomy was performed but at the follow-up after 3 months, there was a recurrent mass and gemcitabine-cisplatin chemotherapy was given. Since a high-grade infiltrating urothelial carcinoma sarcomatoid variant was an aggressive tumor, we need to give more attention to evaluating this tumor.