Sera from 48 subjects with rheumatoid arthritis (RA), more than 80% of which were seropositive, were examined for the presence of antibodies to intact nuclei (ANA) by immunofluorescence, extractable nuclear antigens (ENA), double-stranded DNA by immunoassay and immunoglobulins, i.e. rheumatoid factors (RF) by haemagglutination. The genetic markers of HLA, the fourth complement component (C4) and properdin factor (Bf), which are all coded for within the major histocompatibility complex and Gm immunoglobulin allotypic markers were all analysed in relation to various parameters of these autoantibodies. The only significant association to emerge was between low ENA antibody affinities and the Bf Fs phenotype (p less than 0.02). Although weak associations between individual autoantibody parameters and the other immunogenetic markers were detected, there were no significant HLA, C4 or Gm association with either ANA subsets or RF, a finding which agrees with, and also extends previous HLA studies of predominantly seropositive RA cohorts.