Fifty patients of rheumatoid arthritis clinically diagnosed (by ARA criteria) were studied for both non-organ specific [rheumatoid factor (RF), anti-nuclear antibodies (ANA), extractable nuclear antibody (ENA), granulocyte specific anti-nuclear antibody (GS-ANA), anti-smooth muscle antibody (SMA) and anti-mitochondrial antibody (AMA)] and organ specific, [anti-adrenal (AAA), anti-islet cell (ICA), antithyroid antibody (ATA) and anti-parietal cell (PCA)] auto antibodies. RF was positive in 80 per cent of patients. ANA was positive in 44 per cent of patients, ENA in 62 per cent, SMA in 20 per cent, AMA in 18 per cent and GS-ANA in 68 per cent. Of the organ specific antibodies, PCA was demonstrable in 28 per cent of the patients and none of the other antibodies were present. Circumstantial evidence indicates that ANA and GS-ANA are not synonymous but independent, cross-reacting entities and the presence of both increase the sensitivity (94%) of diagnosis of RA.