 Aprotinin is a serine protease inhibitor, intended to limit blood loss in patients undergoing surgery, was approved for use 13 years ago, and now administered in more than 250,000 surgery patients per year. Although its mechanism of action is not entirely known, it is shown to interfere with contact activation, preserve platelet function, inhibit fibrinolysis, and having some anti-inflammatory effects. Multiple studies have shown its superiority for reducing blood loss over other antifibrinolytics while other studies showing safety concerns regarding early graft closure causing myocardial infarction following coronary bypass surgery, renal failure, vascular thrombosis, and death. Of note, several other studies have addressed such safety concerns- finding that the risk of the aforementioned vascular complications are comparable to results utilizing placebo or other antifibrinolytics such as aminocaproic acid. For example, the associated renal dysfunction was attributed to a competitive excretion process involving creatinine. That is, aprotinin competes with creatinine for elimination by the kidneys such that the apparent renal dysfunction is transient and a false marker of renal injury. However, the issue of renal injury has recently re-emerged as a serious problem in a multicenter study on patients undergoing coronary revascularization, whereby more than two fold increase in postoperative renal dysfunction as well as a nearly two fold rise in postoperative stroke was reported. 