Background and Purpose: Robotic prostatectomy is exploding into popular utilization throughout much of the United States. It is expected that the rise in the number of these cases into 2006 will continue exponentially. A significant amount of research has begun to focus on the anastomosis, because the robot allows unprecedented illumination and dexterous control to make the quality of this repair equal to that of a microscopic approach. Here, we report our results with a circular anastomosis technique using an innovative bidirectional-barbed suture material for knotless, tension-free repair and compare it with a standard polyglecaprone single-knot technique. Materials and Methods: Using a previously described in-vitro model of microfiber synthetic material, a running anastomosis was performed using the da Vinci Surgical System® by one surgeon. Two pre-tied 3-0 polyglecaprone sutures on a tapered Rb-1 needle were compared with a bidirectional-barbed suture (3-0 PDO) designed specifically for our use (Quill Sutures, Research Triangle Park, NC). The times needed to perform the anastomosis, the accuracy in idealized phantoms, and the surgeon's security in the quality of his work (linear scale) were all recorded for 10 consecutive anastomoses. Results: The PDO suture was faster to deploy (17.3 minutes v 19.2 minutes), and the security score by the surgeon was greater. The accuracy was equivalent for both types of running closure comparing the classic van Velthoven with the PDO-sutured anastomosis. Conclusions: It appears from our preliminary work that a bidirectional-barbed suture might improve the vesicourethral anastomosis during a robotic radical prostatectomy. Further investigations should be done to measure the disruptive force necessary to distract these sutures, whether the applied forces of the barbs are adequate for maintaining a watertight seal, and the reproducibility of our results by other surgeons. All of these investigations are in progress in our laboratory.