Background: In recent years, surgeons have begun to report case series of minimally invasive approaches to radical cystectomy, including robotic-assisted techniques demonstrating the surgical feasibility of this procedure with the potential of lower blood loss and more rapid return of bowel function and hospital discharge. Despite these experiences and observations, at this point high levels of clinical evidence with regard to the benefits of robotic cystectomy are absent, and the current experiences represent case series with limited comparisons to historical controls at best. Objective: We report our results on a prospective randomized trial of open versus robotic-assisted laparoscopic radical cystectomy with regard to perioperative outcomes, complications, and short-term narcotic usage. Design, setting, and participants: A prospective randomized single-center noninferiority study comparing open versus robotic approaches to cystectomy in patients who are candidates for radical cystectomy for urothelial carcinoma of the bladder. Of the 41 patients who underwent surgery, 21 were randomized to the robotic approach and 20 to the open technique. Intervention: Radical cystectomy, bilateral pelvic lymphadenectomy, and urinary diversion by either an open approach or by a robotic-assisted laparoscopic technique. Measurements: The primary end point was lymph node (LN) yield with a noninferiority margin of four LNs. Secondary end points included demographic characteristics, perioperative outcomes, pathologic results, and short-term narcotic use. Results and limitations: On univariate analysis, no significant differences were found between the two groups with regard to age, sex, body mass index, American Society of Anesthesiologists classification, anticoagulation regimen of aspirin, clinical stage, or diversion type. Significant differences were noted in operating room time, estimated blood loss, time to flatus, time to bowel movement, and use of inpatient morphine sulfate equivalents. There was no significant difference in regard to overall complication rate or hospital stay. On surgical pathology, in the robotic group 14 patients had pT2 disease or higher; 3 patients had pT3/T4 disease; and 4 patients had node-positive disease. In the open group, eight patients had pT2 disease or higher; five patients had pT3/T4 disease; and seven patients had node-positive disease. The mean number of LNs removed was 19 in the robotic group versus18 in the open group. Potential study limitations include the limited clinical and oncologic follow-up and the relatively small and single-institution nature of the study. Conclusions: We present the results of a prospective randomized controlled noninferiority study with a primary end point of LN yield, demonstrating the robotic approach to be noninferior to the open approach. The robotic approach also compares favorably with the open approach in several perioperative parameters. © 2009 European Association of Urology.