The Leapfrog Group aims to improve patient safety and outcomes in hospitals through promoting the routine use of evidence-based medicine (EBM) practices such as the perioperative use of beta-blocker medications during elective abdominal aortic aneurysm (AAA) repair. The emergence of recent evidence, however, has sparked debate about the benefits of this practice. We found that implementation of the Leapfrog Group's beta-blocker standard in California hospitals has led to an estimated 50 percent decrease in mortality following open AAA repair over time. The efficacy and effectiveness of specific EBM practices must be continually reexamined, to ensure that objectives are being met.