A case of transitional cell carcinoma in the ureter showing inverted proliferation is reported. A tumor in the middle third of the right ureter was found in a 67-year-old male complaining of gross hematuria. Since positive findings of malignancy were obtained in a washing examination of urine cytology, right nephroureterectomy was performed. The gross specimen consisted of a polypoid and pedunculated 22 x 8 mm tumor which showed a smooth surface as in normal ureteral mucosa. Histopathologically, the tumor was lined with normal transitional epithelium but filled with transitional cell carcinoma, grade 1. Diagnosis and treatment of ureteral tumors showing inverted proliferation are discussed.