Four multiplex families affected with adult polycystic kidney disease were investigated for segregation of the disease with haplotypes bearing HLA-A and B antigens and Bf allotypes. In no case did the disease travel with specific haplotypes within families showing an absence of linkage between the disease and the major histocompatability system. In addition, the disease was not associated with any HLA-A or B antigen or Bf allotype either within or among the families studied.