This study reports the frequencies of the alloantigens of four major platelet-specific alloantigen systems among Indonesians. One hundred and sixty-eight unrelated Indonesian blood donors were phenotyped for the alloantigens of the Zw (PIA, HPA-1), Bak (HPA-3), Yuk (Pen, HPA-4), and Br (HPA-5) systems by use of a glycoprotein-specific immunoassay. All were positive for the alloantigens Zwa, Yukb, and Brb. Three (1.79%) and 1 (0.59%) of the 168 donors were positive in testing for Zwb and Yuk(a) antigens, respectively. Fifteen (9.26%) of 162 Indonesians had Br(a) antigens. Of the 166 donors tested, 121 (72.89%) were Bak(a) positive and 134 (80.72%) were Bakb positive. In addition, the phenotype frequency of Nak(a) was determined by using monoclonal antibody OKM5 in a platelet enzyme-linked immunosorbent assay. Its frequency in the present cohort was 95.83 percent (161/168). This study confirms the differences in platelet antigen distributions in Asians and whites. Both glycoprotein IV deficiency and the Yuk polymorphism are also found among Indonesians.