Objectives To determine the effect of prostate weight (PW) on robotic laparoscopic radical prostatectomy (RLRP) outcomes. The effect of PW on surgical and pathologic outcomes has been reviewed in open and laparoscopic prostatectomy series. Little is known about its effects during RLRP. Methods From February 2003 to November 2005, 375 men underwent RLRP. Patients were divided into four groups on the basis of the pathologic PW: group 1, less than 30 g; group 2, 30 g or more to less than 50 g; group 3, 50 g or more to less than 80 g; and group 4, 80 g or larger. The groups were compared prospectively. Continence and sexual function were assessed using validated questionnaires. Results Of the 375 patients, 20, 201, 123, and 31 had a PW of less than 30 g, 30 g or more to less than 50 g, 50 g or more to less than 80 g, and 80 g or larger, respectively. A significant difference was found in age and prostate-specific antigen values among the four groups ( P <0.001). No significant differences in operative time, estimated blood loss, transfusion rate, hospital stay, length of catheterization, and complication incidence were observed among the four groups. The overall rate of positive surgical margins was significantly different among the groups ( P = 0.002), demonstrating a trend of increasing positive surgical margins with a lower PW. Within the patients with Stage pT2, a significant increase in positive surgical margins was found with lower PWs ( P = 0.026). The objective return of baseline and subjective sexual and urinary function, as determined by questionnaire scores, was not affected by the PW. Conclusions RLRP can be performed safely and with similar perioperative outcomes in men, regardless of the PW. We found a significant inverse relationship between surgical margin status and PW, specifically in those with Stage pT2 disease.