Background and Objectives: Erectile function after prostate surgery is an important criterion for patients when they are choosing a treatment modality for prostate cancer. Improved visualization, dexterity, and precision afforded by the da Vinci robot allow a precise dissection of the neurovascular bundles. We objectively assessed erectile function after robot-assisted extraperitoneal prostatectomy by using the SHIM (IIEF-5) validated questionnaire. Methods: Between July 2003 and September 2004, 150 consecutive men underwent da Vinci robot-assisted extraperitoneal radical prostatectomy for clinically localized prostate cancer. The IIEF-5 questionnaire was used to assess postoperative potency in 67 patients who were at least 6 months postsurgery. Erectile function was classified as impotent <11), moderate dysfunction (11 to 15), mild dysfunction (16 to 21), and potent (22 to 25). All patients used oral pharmacological assistance postprocedure. Results: Sixty-seven patients were available to complete the IIEF-5 questionnaire 6 months to 1 year postprostatectomy. Twelve patients were excluded from the study who abstained from all sexual activity after surgery for emotional or social reasons. Of the 55 patients evaluated, 22 (40%) were impotent, 3 (5.5%) had moderate erectile dysfunction (ED), 12 (21.8%) had mild ED, and 18 (32.7%) were fully potent. The table compares IIEF-5 scores with nerve-sparing status. Of patients who had bilateral nerve sparing, 28/45 (62.2%) had mild or no ED within 6 to 12 months postsurgery, and all expressed satisfaction with their current sexual function or rate of improvement after robotic prostatectomy. Conclusion: Robot-assisted extraperitoneal prostatectomy provides comparable outcomes to those of open surgery with regards to erectile function. Assessment of the ultimate maximal erectile function will require continued analysis, as this is likely to further improve beyond 6 to 12 months.