A case of graft-versus-host disease (GVHD) associated with blood transfusion in a 71-year-old man is reported. The patient received transfusions (irradiation red cells M.A.P 14 units, fresh frozen plasma 11 units) and developed features of GVHD including fever, a skin rash, diarrhea, liver dysfunction, hypoplastic bone marrow, and pancytopenia. He died on day 32 posttransfusion. Pathologically, lymphocyte infiltration of skin and liver lesions, degeneration of small bile ducts, crypt cell necrosis in the gastrointestinal tract, and bone marrow hypoplasia were observed. Immunohistochemically, infiltrating lymphocytes were CD8+ T type, the result suggesting that they role a part in posttransfusion GVHD.