Abstract Introduction and Objectives: Radical prostatectomy (RP) is associated with a high risk of intraoperative blood loss and subsequent bloodtransfusions. The shift in surgical technique from open radical prostatectomy (ORP) to robot-assisted radical prostatectomy (RARP) has resulted in lower operative blood loss, and reduced the need for transfusions. We analyzed the American College of Surgeons National Surgical Quality Improvement Project (ACS-NSQIP) database to compare real-world, contemporary trends in utilization and timing of blood transfusion following ORP and RARP. Methods: We identified men undergoing both RARP and ORP and then queried for patients who received a blood transfusion in the perioperative period. The outcomes of interest were need and timing of perioperative blood transfusion (PBT), which was categorized into early (postoperative day [POD] ≤1) or late (POD ≥2). Logistic regression analysis was used to identify variables associated with the need and timing for PBT. Results: A total of 16,144 men who underwent RP were identified from 2007 to 2012. The overall PBT rate was 3.1%. Highest rate of transfusions occurred on day of surgery for patients undergoing ORP, and first POD for patients undergoing RARP. On multivariate analysis significant predictors of blood transfusion included history of bleeding disorder (OR: 2.8, p=0.002), preoperative dyspnea (odds ratio [OR]: 1.7, p=0.03), starting hematocrit <42% (OR: 1.9, p<0.001), open approach (OR: 0.09, p<0.001), year of surgery (OR: 0.5, p<0.001), resident involvement (OR: 1.6, p=0.003), and operative time (OR: 4.4, p<0.001). The only predictor of receiving a blood transfusion on POD 2 or later was having the procedure performed through a robot-assisted approach (OR: 3.7, p<0.001). Conclusions: In this study we found that the rate of perioperative transfusions is lower than previously published. A clear separation in timing of transfusion exists based on the utilized surgical approach. It is prudent that surgeons performing RARP be aware of the low, but present risk of a delayed blood transfusion.