Transfusion associated graft versus host disease (TA-GVHD) is a rare but lethal complication of transfusion,1 generally associated with immunosuppressed patients. As described in the case report in this issue,2 however, the condition can occur in fully immunocompetent individuals, with the onset of symptoms usually 1–2 weeks after transfusion. Patients experience the classic features of GVHD: skin rash, diarrhoea, fever, and hepatitic liver damage with or without jaundice. What makes TA-GVHD so devastating is the involvement of the bone marrow, with severe hypoplasia leading to profound pancytopenia. The disease then follows a downhill course with death, usually caused by infection, in more than 90% of cases. Once established, the condition is not amenable to treatment. Fortunately, it appears to be entirely preventable if cellular blood components (red cells and platelets) are γ irradiated before transfusion. This is currently performed only for patients deemed at particular risk of TA-GVHD; however, recognition and reporting of cases in other patient groups is extremely important. Only in this way can new risk factors be recognised, and irradiated components provided.