SUMMARY Nineteen different HLA haplotypes were observed in 23 Japanese families with 46 parents and 92 chromosomes. Certain combinations of antigenic factors in the haplotypes were more frequent than others. The association between HLA determinants were different in Orientals, Negroes, and Caucasians. It is likely that these associations of phenotypes reflect the frequency of the different haplotypes in different races. Gene frequencies varied considerably in the three races and, in the extreme example, HL-A1 and HL-A8 were absent in Orientals. No evidence for the selective advantage of heterozygotes was obtained for any HL-A determinant by segregation analysis and by inheritance in Japanese families. Also, no selection against particular types of children was observed. A new antigen, Te 13, is described and its association with the known antigens is studied in three races.