Clinical syndromes resembling autoimmune diseases have been reported in women who have had breast augmentation procedures. To see whether there is a humoral immune response in these diseases that is similar to the immune response in their idiopathic counterparts, we assessed the immunological specificity of antinuclear antibodies (ANAs) and certain epidemiological features in 24 patients, all of whom (with 1 exception) had received silicone gel breast implants. ANA specificities were identified by indirect immunofluorescence, immunodiffusion, western blot analysis, and immunoprecipitation of radiolabelled intracellular proteins. Of 11 patients who had symptoms and signs that met criteria for defined autoimmune diseases, 7 had scleroderma or subsets of this disorder and the others had systemic lupus erythematosus, rheumatoid arthritis, or overlapping autoimmune diseases. High ANA titres were present in 10 of these 11 patients and the ANA specificities were similar to those found in the idiopathic forms of the corresponding autoimmune diseases. Trauma, with resultant rupture of implants, accelerated onset of symptoms. 13 other patients had autoimmune disorders of a less clearly defined nature and low titres of ANAs whose specificities could not be identified. ANAs are associated with the development of autoimmune complications in women with silicone breast implants. Further studies are needed to see whether this relation is one of cause and effect and whether ANAs might be early serological markers preceding development of autoimmune symptoms.