Rheumatoid factors of the IgA isotype directed to human IgG Fc fragment were assayed, using an Elisa test, in the serum of 30 patients with seropositive rheumatoid arthritis and in the synovial fluid of 9 of them. A high incidence was found in the serum (90%) and synovial fluids (77%). Clinical, radiological and biological parameters of each patients were recorded at the time of the assay, and two years later. There was no statistically significant association between IgA rheumatoid factors levels and other parameters, nor with a pejorative evolution. However, a significant negative correlation was observed between IgA rheumatoid factors levels and the duration of the disease, suggesting that IgA rheumatoid factors are predominantly produced at the earliest stages of rheumatoid arthritis.