As solid organ transplantation becomes increasingly common and complex, the demands on the transfusion service expand. Transplant recipients present unique challenges not only because of product availability but also because of specialized blood components, serologic problems, and immunologic effects of transfusion on the allograft and the recipient. Solid organ transplant recipients receive immunosuppressive agents that make them more susceptible to infectious or immunologic complications of transfusion such as cytomegalovirus infection and graft-versus-host disease. Other immunologic consequences of transfusion such as alloimmunization may also be severe, resulting in acute or chronic graft rejection. The transfusion specialist must recommend the optimal approach to reducing the risk of these complications in organ transplant recipients.