An association between systemic lupus erythematosus (SLE) and immunoglobulin A (IgA) deficiency has been reported previously and may have therapeutic consequences for patients who require treatment with intravenous immunoglobulin. We report the prevalence of IgA deficiency in a clinic population of 96 patients with SLE. Five patients were found to be consistently IgA deficient. These patients were more likely to be West Indian, to have anti-Sm and anti-La antibodies and to have a speckled pattern of antinuclear antibody. There were no significant differences in clinical features between IgA deficient and other SLE patients, nor in SLE-related HLA alleles. We thus confirm the increased prevalence of IgA deficiency in patients with SLE. A review of the literature is presented and we speculate on the nature of the link between IgA deficiency and SLE.