TA-GvHD is a rare transfusion complication that results from an immune response in which the donor’s T lymphocytes attack the transfusion recipient’s lymphoid tissue. Normally, the immune system of the transfusion recipient recognizes the donor’s lymphocytes as foreign and destroys them through the immune system, but when the transfusion recipient is an immunocompromised person (e.g., congenital immunodeficiency, acquired immunodeficiency, tumor, etc.) or when the donor and transfusion recipient are identical twins and immediate relatives (human leukocyte antigen – HLA is semi-identical), the transfusion recipient’s immune system may not be able to destroy the donor’s lymphocytes, which then leads to TA-GvHD. The chance of TA-GvHD in immunocompromised individuals is 0.1-1.0%, with a morbidity and mortality rate of 80-90%, which is significantly higher than that of graft-versus-host disease after hematopoietic stem cell transplantation (GvHD). The most common cause of death in TA-GvHD is infection and bleeding secondary to complete cytopenia and abnormal liver function. infections and bleeding from abnormal liver function. TA-GvHD can occur 4-30 days after transfusion and has symptoms similar to GvHD after HSCT. Typical symptoms include fever, rash and even epidermal necrosis. Other symptoms include cough, abdominal pain, vomiting and diarrhea. Laboratory tests reveal complete cytopenia, abnormal liver function and electrolyte disturbances due to diarrhea. Diagnosis can be confirmed by biopsy of the affected skin and detection of lymphocytes in the transfusion recipient’s blood that differ from the transfusion recipient’s HLA. Effective treatment for TA-GvHD is lacking and relies mainly on supportive therapy. Therefore, prevention of TA-GvHD is important. The preventive measure is to irradiate blood products containing lymphocytes with gamma radiation before transfusion in order to destroy the function of the lymphocytes in the blood product. Blood products should be irradiated in the following cases: 1) when the transfused person is immunocompromised; 2) when the blood component is from a family member; 3) when the platelets are of the same HLA type (special matched platelets).