Sera from 151 children of whom 112 had juvenile chronic polyarthritis (JCP), and from adults with rheumatoid arthritis (RA), and from healthy pregnant females were tested for the presence of granulocyte-specific antinuclear antibodies (GS-ANA). These were detected in 20% of sera from cases of JCP, in 68% of adult RA, but in none of the controls. Eosinophil-specific ANA were the only ANA present in 18% of positive children and 54% of the positive adults. GS-ANA in children were predominantly IgG and of low titre. Heat-stable GS-ANA were detected in sera from eight children but none bound complement. The presence of GS-ANA was not significantly associated with sex, age of onset, duration of disease, mean active joint count, mean ESR, nor with the presence of fever, rash, splenomegaly, amyloidosis, pericarditis, or rheumatoid factor.