Among patients with metastatic urothelial cancer of the bladder, 16-25% develop peritoneal carcinomatosis. In the majority of cases peritoneal carcinomatosis is associated with multiple metastatic sites. Peritoneal metastases as the single site of metastatic deposits are rare and they have been described following laparoscopic radical nephroureterectomy or cystectomy. We report on a patient who developed peritoneal carcinomatosis as the single site of metastases 8 months after robotic-assisted radical cystectomy, extended pelvic lymphadenectomy and extracorporeal formation of an ileal neobladder for organ-confined, muscle-invasive and poorly differentiated bladder cancer. The indication for robotic-assisted radical cancer surgery for urothelial carcinoma of the upper or the lower urinary tract in patients with locally advanced or poorly differentiated cancer should be made with caution.