OBJECTIVE: To assess variability in the vascular structures of the presacral space and to estimate the risk of injury because of blind suture placement during sacral colpopexy. STUDY DESIGN: Ten fresh frozen female cadavers were evaluated. Three 0-polyester sutures were placed blindly through the peritoneum and around the midline of the anterior longitudinal ligament. The presacral space was dissected and the sutures examined for injury to vessels. The midline of the anterior longitudinal ligament was marked from the promontory to its inferior edge, and measurements were taken to the leading edge of vessels proximal to the presacral space. On a template, all vessels larger than 2 mm were drawn to scale and overlaid on the template. RESULTS: Unequivocal vascular injury was found in 5 cadavers because of blind sutures. Four injuries occurred to the middle sacral artery and 1 to the left common iliac vein. There was significant variability in location of vessels, particularly on the left side of the ligament. CONCLUSIONS: The vascular pattern of the presacral space is variable, and major vessels may deviate significantly from their expected positions. Surgeons should carefully expose this space prior to placing sutures during sacral colpopexy.