This study evaluated the effect of blood on the antimicrobial activity of several agents used for handwashing. Seventy-one healthy adult volunteers used 1 of 6 products (70% isopropyl alcohol [IPA]; liquid hand rinse containing 70% ethyl alcohol and 0.5% chlorhexidine gluconate [EA]; detergent containing 7.5% povidone-iodine [PI]; detergent containing 4% chlorhexidine gluconate [CHG]; a nonantimicrobial soap; and a control group that used no product) in two tests: with and without 1.2 mL of dried sterile sheeps' blood on the hands. In the presence of blood, the two alcohol products (IPA and EA) resulted in significantly greater reductions in numbers of colony-forming units than other products (P less than 0.001). When no blood was present, IPA was associated with significantly greater reductions, whereas soap and control groups had significantly lower reductions (P = 0.008). We conclude that hands are effectively degermed with a variety of products in the presence of blood, and that alcohols give greater initial reductions in colonizing flora. This is of particular relevance in emergency situations during which contamination with blood is likely and handwashing facilities are inaccessible.