During the past year, blood component therapy witnessed two quite contradictory trends in the area of leukoreduction. On the one hand, the year saw widespread forced implementation of leukoreduction by several national blood suppliers, including the American Red Cross, who refused to sell hospitals nonleukoreduced blood. The forced implementation came at high cost to hospitals and with the strong endorsement of the US Food and Drug Administration, which stopped short of mandating universal leukoreduction in the United States. On the other hand, the year saw the publication of several pivotal clinical trials that failed to demonstrate significant patient benefit from the use of leukoreduced blood components. The emerging scientific and clinical evidence reviewed in this article demonstrates that leukoreduction technology is an effective means to reduce the risk of three complications of transfusion: HLA alloimmunization, cytomegalovirus transmission, and recurrent febrile nonhemolytic transfusion reactions. The application of the technology to all blood components does not appear to be warranted.