Alloimmunization against donor leukocyte antigens may potentially cause rejection of solid-organ transplants via cross-immunization. This is mediated by the HLA-antigen system. Matching of HLA antigens is most important for kidney and heart transplants and least important for liver transplants. Therefore, using leukocyte-depleted blood products to prevent HLA alloimmunization is most logical for potential recipients of kidney and heart transplants. In liver transplantation, leukocytes in the intraoperatively administered blood have been suggested as a contributor of acute cellular rejection via an inflammatory cascade, although there are no randomized, controlled trials to support the benefit of leukocyte depletion for this indication. Overall, there is reasonable evidence for the benefit of using leukocyte-depleted blood products to prevent graft rejection in future recipients of kidney transplants, whereas the data are insufficient regarding heart transplants. Leukocyte-depleted blood products are not indicated for liver transplant candidates, at least for the purpose of preventing HLA alloimmunization.