Abstract Objectives To assess the preoperative parameters and clinical outcomes of patients undergoing robotic laparoscopic radical prostatectomy with specific attention to the body mass index (BMI). Little is known about the impact of obesity (BMI greater than 30) on the clinical outcomes of patients undergoing radical prostatectomy. Methods The data of 100 men undergoing robotic laparoscopic radical prostatectomy between June 2002 and October 2003 were prospectively entered into a database. The standard clinical characteristics (eg, prostate-specific antigen, Gleason score) and perioperative and postoperative parameters were evaluated. Additionally, all were assessed preoperatively and postoperatively for American Urological Association symptom and bother scores, uroflowmetry, postvoid residual urine volume, and sexual function. Results Nineteen men were obese (BMI greater than 30) and 81 were not (BMI less than 30). The two groups had a similar need for transfusion, length of stay, and pathologic outcome. However, the obese men had poorer baseline urinary function (peak flow rate 13.9 versus 18.3 mL/s; voided volume 306 versus 454 mL; P ≤0.05) and sexual function (Sexual Health Inventory of Men score 14.1 versus 18.2; P ≤0.05). Obese men had significantly more complications (26.3% versus 4.9%; P = 0.01) and required more time to return to baseline activities (7 versus 4.3 weeks; P = 0.09) and urinary function. Finally, at 6 months, only 47% of obese patients versus 91.4% of nonobese patients had achieved pad-free urinary continence ( P ≤0.001). Conclusions In this study, obese patients had significantly worse baseline urinary and sexual function, had complications, and did not recover urinary function as quickly or as well as nonobese patients. Obese patients also demonstrated a strong trend toward a delay in recovery time.