A 76-year-old male visited the emergency room in June 2014 because of left flank pain. His past medical history was significant for advanced prostate cancer treated with androgen deprivation therapy (ADT). According to medical records, he first presented at our outpatient department with urinary obstructive symptoms and was diagnosed with prostate cancer (clinical stage T3bN0M0), with an initial serum prostate specific antigen (PSA) level of 80.69 ng/ml 2 years earlier. At that time, we recommended ADT plus radiation for the treatment of the prostate cancer. However, the patient only received ADT. After 9 months of complete androgen blockade therapy, the PSA had decreased to 0.39 ng/ml, but the patient was lost to follow-up and treatment. When he again presented at the emergency room in June 2014, the PSA level was 6.75 ng/ml. Abdominal computed tomography (CT) revealed a left distal ureteral enhancing mass about 2.1 cm in length causing hydronephrosis, and no lymphadenopathy. We initially performed left percutaneous nephrostomy for symptomatic hydronephrosis. Retrograde pyelography showed smooth, marginated filling defects in the left distal ureter. Cytology showed no pathological results. Because of suspected urothelial cell carcinoma of the left distal ureter, nephroureterectomy with bladder cuff excision was performed. Pathological examination revealed a lesion consisting of hyperchromatic cells around the ureter. Immunohistochemical staining was strongly positive for prostate cancer markers, including p504S, PSA, and ERG, and negative for p63. These findings confirmed a diagnosis of prostate carcinoma metastatic to the left ureter, with no evidence of urothelial cell carcinoma. The tumor invaded the adventitia and muscularis of the ureter, but the distal ureteral surgical margin was not involved by tumor cells. After the operation, the patient was treated with complete androgen blockade therapy. However, at the 3-month follow-up, the PSA level increased to 8.73 ng/ml. At the 1-year follow up, further progression with multiple bone metastases, metastatic lymphadenopathy, and right ureteral metastasis led to docetaxel chemotherapy following enzalutamide therapy, but terminating in death after the year.