Drotrecogin alfa (activated), a recombinant form of human activated protein C, is the first therapeutic intervention shown to reduce all-cause mortality in severe sepsis. In the Phase 3 study (F1K-MC-EVAD; PROWESS), 1690 patients were randomly assigned to receive a 96-hour intravenous infusion of drotrecogin alfa (activated) 24 micrograms/kg/h or placebo (850 patients and 840 patients, respectively). Overall, administration of drotrecogin alfa (activated) yielded a clinically significant reduction in 28-day all-cause mortality: 24.7% of drotrecogin alfa (activated) patients died versus 30.8% of placebo patients (19.4% relative risk reduction; p=0.005; Bernard et al. 2001). The only safety concern noted in the Phase 3 trial was an increased risk of serious bleeding among drotrecogin alfa (activated) patients (3.5% versus 2.0% of placebo patients). The difference between the two treatment groups in the number of patients who experienced a serious bleeding event was due to the greater number of drotrecogin alfa (activated) patients who experienced a serious bleeding event that was related to a procedure (for example, bleeding that resulted from the placement of a catheter or nephrostomy tube). The number of patients who experienced spontaneous serious bleeding events was similar between the two treatment groups.