One of the recent developments in the da Vinci robot surgical system is the introduction of a more ergonomic four-arm robot. We report our experience of robotic radical cystectomy (RRC) for bladder cancer using the four-arm da Vinci(®) S(TM) robot (Intuitive Surgical, Sunnyvale, CA, USA). Beginning September 2006, we performed robotic radical cystectomy and bilateral pelvic lymphadenectomy in six patients with muscle-invasive bladder cancer using da Vinci(®) S(TM) robot. Ileal conduit diversion was made in five patients, and sigmoid orthotopic neobladder in one patient. The operating surgeon used the fourth arm for various steps such as bladder retraction for defining vascular pedicles, separating cystoprostatectomy specimen off the rectum, and while performing urethroneovesicostomy. The mean operative time was 12, 148, 44, and 126 min for docking, cystectomy, lymphadenectomy, and urinary diversion, respectively. Median blood loss was 200 ml. Mean hospital stay was 9.2 days. Surgical margins were negative in all the patients. The mean number of nodes removed was 12 (4-19). Histopathology revealed transitional cell carcinoma in all the patients (pT2a-1, pT2b-3, pT3a-2). Robotic radical cystectomy is feasible with new four-arm da Vinci(®) S(TM) surgical system. The operating surgeon can use the fourth arm of the robot as a substitute for the second assistant during the procedure. However, a patient-side surgeon with adequate training in laparoscopic skills is mandatory.