We report two cases of left ureteral carcinoma that may have been related to prior radiotherapy and anticancer chemotherapy for stage II testicular seminoma. Both patients had undergone radiotherapy (60 Gy) and cisplatin-based chemotherapy, one 17 years before the present presentation and the other 24 years earlier. They underwent retroperitoneoscopy-assisted left nephroureterectomy under a diagnosis of left upper ureteral cancer, established by means of ureteroscopy and brush biopsy. The urologic and radiologic outcomes have been satisfactory after more than 2 years of follow-up. Recently, some investigators have reported that testicular cancer survivors are at significantly increased risk of solid tumors for at least 35 years after treatment. Young patients may have a high risk of cancer when they reach an advanced age.