OBJECTIVES: New treatments in prostate cancer intend to have more precise techniques to reduce side effects and improve quality of life. The aim of this study was to estimate health related quality of life of patients with localized prostate cancer undergoing robot-assisted laparoscopic prostatectomy or conventional open prostatectomy. METHODS: Prospective cohort study was conducted from March 2014 to January 2015. All patients that were diagnosed with localized prostate cancer answer the EQ -5D 3L and then went to robot-assisted laparoscopic prostatectomy or conventional open prostatectomy as recommended by their doctor. They also answered the questionnaire at hospital discharge and at six month follow-up using, in a reference cancer hospital in Rio de Janeiro.   RESULTS: Median age was 60.06 years, prostate specific antigen in the open surgery was 9.25±4.59 ng/dl and   8.15±4.34 ng/dL in the robotic surgery, blood loss was higher in the open surgery. Among the 18 patients in the open surgery and the 27 in the robotic surgery the most significant result was the loss of quality of life in the group of open surgery at hospital discharge with less 10 points in the VAS and less 10.9% in utility (statistically and clinically significant) comparing to baseline. The difference between the two techniques is 11% when observed the loss in the VAS of the open surgery group and the gain in the robotic surgery. At six months the change in quality of life was not significant when compared to baseline, suggesting that this is not sustained over time. CONCLUSIONS: This study helps in discussion about the benefits of robotic prostatectomy over the open procedure. Even with a significant difference between the two techniques in the immediate postoperative period favoring robotic surgery, this difference was not maintained at six months, which may not justify the higher costs of this procedure.