The frequencies of platelet-specific antigens among Oriental populations have not been well studied. This article reports the determination of the frequency of five major platelet-specific antigens among Korean blood donors. Both the PlA1 (Zwa) and Yukb antigens were positive in all of the 126 Koreans tested. Baka and Yuka antigens were positive in 110 (87.3%) and 2 (1.6%) of the 126 subjects, respectively. Ten (11.5%) of 87 Koreans had PlA2 (Zwb) antigens. A simplified immunofluorescence test, the adhesion slide immunofluorescence test, was devised for platelet antigen typing.