The incidence of aplastic anemia is reported to be higher in Asia than elsewhere. We studied the frequency of human leukocyte antigen (HLA) DRB1 alleles in aplastic anemia patients from 2 genetically similar aboriginal groups, the Kadazan and the Dusun, and compared them with genetically matched community and hospital controls. HLA-DRB1*15 was significantly higher in the patients compared with controls (p = 0.005), confirming similar findings in Japanese and Caucasian studies. Further testing indicated a significantly higher frequency of HLA-DRB1*1501 in patients compared with controls (p = 0.0004) but no significant difference in the frequency of HLA-DRB1*1502. The high frequency of HLA-DRB1*15 in the Kadazan and Dusun population combined with the wide variety of environmental factors associated with aplastic anemia could be the reason for the elevated incidence of aplastic anemia in the Kadazan and Dusun in Sabah.