Many medical institutions in Korea have recently been performing an antibody screening test as one of the essential elements of a pre-transfusion test. The Di^a antigen is well known as one of the antigens with low incidence among Caucasians; however, it has been discovered with a relatively higher incidence among Mongoloid populations. The frequency of the Di^a antigen among the Korean population is estimated to be 6.4-14.5%. But in Korea, a screening panel of cells from abroad without Di^a positive cells has been commonly used when a patient has an unexpected antibody screening test. Here we report a case of acute hemolytic transfusion reaction due to Anti-Di^a antibody. To prevent other transfusion reaction by anti-Di^a antibody, addition of Di^a positive cells as unexpected antibody screening test is recommended.