Thirty couples having a DS child were typed for HLA-A and B antigens and compared to twenty control families and 176 blood donors. Although differences in frequency of B antigens exist between DS families and controls, they are not significant after correction for the number of antigens tested. No excessive HLA sharing was found in DS parents contrarily to two previous studies (Mattironi et al. 1981, Aymé et al. 1983).