2 fatal cases of graft-versus-host disease (GvHD) occurred following blood product transfusions given to patients receiving standard chemotherapy for Hodgkin’s disease. GvHD was established by HLA typing, clinical course, and compatible skin biopsy. 23 cases of GvHD following transfusion of blood products from normal donors are also reviewed. It should be suspected when fever or rash appear 1–2 weeks after transfusion of unirradiated blood products into a compromised host or when pancytopenia following chemotherapy is prolonged or unexpectedly severe. Prevention of GvHD by irradiation of granulocytes, platelets and packed red blood cells given to immunosuppressed patients is recommended to prevent this often fatal disease