It is widely accepted that blood transfusions can cause allosensitization, but it is often reported that new human leukocyte antigen (HLA) antibodies are nonspecific and transient. This study explores the effect of blood transfusion on allosensitization in waitlisted transplant patients including the development of transfusion-specific antibodies (TSAs), while they remain on the waiting list, with longitudinal follow-up of subsequent transplantation. A total of 105 blood donors of transfusions received by 50 patients on the transplant waiting list were HLA typed.