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. Thus, it has been speculated that the incidence of unexpected antibody against the Di^a antigen might be relatively higher among these populations. Hemolytic transfusion reactions (HTRs) and hemolytic disease of the newborns (HDNs) caused by anti-Di^a have been reported sporadically. However, there has been no prospective study on the incidence of anti-Di^a in Mongoloid populations particularly. The authors conducted a series of antibody screening tests on 11,219 Korean individuals for 25 months, by using three kinds of screening cells including Di^a cell. Anti-Di^a was detected in 8 patients, seven of whom had a history of transfusions or were multigravida. The incidence of anti-Di^a measured in this study was higher than expected, ranked third among unexpected antibodies identified during the period of the study, so it is strongly recommended that the Di^a+ panel cell must be incorporated into antibody screening test for safer transfusion in Asian-Mongoloid populations.