Graft-versus-host disease (GVHD) refers to organ dysfunction resulting from the introduction of foreign immunocompetent lymphocytes or bone marrow tissue (the graft) into an immunologically defective host. Acute GVHD in infants is usually secondary to engraftment of maternally transmitted or transfusion-derived T lymphocytes in infants with severe combined immunodeficiency (SCID). Acute disease typically presents as a morbilliform eruption that may progress to erythroderma or a toxic epidermal necrolysis-like picture.