Ninety children with definite juvenile dermatomyositis (JDMS), who had been HLA typed, were tested for the presence of tissue or organ-specific antibodies. Sixty had active disease at the time of study. The mean disease duration was 4 years, and 30 had soft tissue calcifications. The following autoantibodies were sought: thyroid, gastric parietal cells, smooth muscle, striated muscle, microsomes, mitochondria, DNA, extractable nuclear antigen, Sm, PM-1, antinuclear antibody (ANA), and rheumatoid factor. Only the ANA and PM-1 were more frequent in patients than in controls (P less than 0.0002 and P less than 0.001, respectively). Higher levels of immune complexes (P less than 0.01) were found in sera from patients with JDMS than in sera from controls and were correlated with the presence of ANA in patients (P less than 0.01). Soft tissue calcification was not associated with any autoantibody or HLA antigen, but with disease duration and activity (P less than 0.001 and P less than 0.05, respectively). There was no association between the occurrence of any autoantibody and the presence of HLA-B8 or DR3 among the white patients with JDMS. The frequency of autoantibodies in 43 full siblings of children with JDMS was not increased. We conclude that children with JDMS, with or without HLA-B8/DR3, do not show evidence of a generalized nonspecific antibody response to tissue antigens. The significance of the increased antibody to nuclear antigens ANA and PM-1 remains to be determined.