SUMMARY
Antibody responses to the polysaccharide antigens of bacterial lipopolysaccharides and their hapten derivatives are herein documented to be under multigenic control. Among the genes responsible for the antibody response to these polysaccharide antigens include those coded for by genes located on the X chromosome and those on chromosome 17 linked to genes in the H‐2 and/or Qa loci. The use of B10 congenic mice revealed that two genes on chromosome 17 are involved in the regulation of the antibody response to bacterial polysaccharide antigens. The use of CXB recombinant inbred mice confirmed the multigenic control of the antibody response within their background array of genes. The data clearly demonstrate that immune responses to these polysaccharide antigens are under genetic control, the importance of which may be of significance with regard to humoral protection during gram‐negative infection.