Objective To study early diagnosis and treatment of Wernicke's encephalopathy(WE) in allogeneic peripheral blood stem cell transplantation recipients.Method A 17 years old patient with acute B-lymphocytic leukemia received HLA-matched nonrelative allogeneic peripheral blood stem cell transplantation after conditioning with total-body irradiation/idamycin/cyclophosphamide (TBI/IDA/Cy) regimen.CD25 monoclonal antibody and cyclosporine A+mycophenolate mofetil + methotrexate were administrated for graft versus host disease prophylaxis.Result On the day 8,the platelet was over 20 × 109/L; On the day 10,the neutrophile granulocyte was over 0.5 × 109/L; On the day 28,full engraftment was confirmed by a bone marrow medicolegal identification.The continued nausea and vomiting after HSCT resulted in deficiency of intake and malabsorption.On the day 54,illusion and tremor occurred,and the follow-up brain MRI suggested WE,but the patient died before thiamine replacing therapy.Conclusion WE is also a rare neurologic complication of HSCT,however,it can easily be overlooked.So early radiologic surveillance and treatment for patients with WE is very important to minimize central nervous system complications and unwanted mortality.