Transfusion-related acute lung injury (TRALI) is a serious clinical syndrome that is temporally associated with the transfusion of plasma-containing blood components. The syndrome typically occurs within 6 hours of transfusion. Approximately 80 percent of cases will resolve within 96 hours with supportive care. The syndrome has been associated with antibodies to WBC antigens and generation of biologically active mediators in stored cellular blood components. Appropriate laboratory investigation of TRALI can be crucial in confirmation of the clinical diagnosis, as well as in decisions regarding donor management.