We report a case of port-site metastasis of bladder cancer after left retroperitoneoscopy-assisted nephroureterectomy and cystectomy. The patient was a 73-year-old man with a chief complaint of gross hematuria. The diagnosis was invasive bladder cancer with bone metastasis. He received two courses of chemotherapy (methotrexate, vinblastine, adriamycin, cisplatin), and this resulted in resolution of the bone metastases. Two months later, abdominal and pelvic computed tomography showed a bladder tumor invading the left lower ureter with hydronephrosis. Left retroperitoneoscopy-assisted nephroureterectomy and cystectomy were performed. The patient was unable to undergo systemic chemotherapy because of renal dysfunction. Four months later, a lateral abdominal wall tumor was found at a port-site, and needle biopsy confirmed this to be metastatic urothelial carcinoma. Clinicians need to be aware of port-site metastasis, particularly in patients with UC, and take steps to prevent it during laparoscopic procedures.