The relationship between IgA anti-dsDNA antibodies and systemic lupus erythematosus (SLE) disease activity was investigated. IgA anti-dsDNA antibodies were measured using ELISA techniques. Elevated serum levels of IgA anti-dsDNA antibodies were detected in 51% of the patients with SLE (n = 57) and 8% of the diseased controls (n = 214). The presence of IgA anti-dsDNA antibodies was associated with kidney and joint abnormalities, with hypocomplementemia and with circulating immune complexes. We conclude that increased levels of IgA anti-dsDNA antibodies are associated with disease activity in patients with SLE.