Diverse immunologic abnormalities have been described in women who received silicone breast implants. However, most studies have focused on either a limited number of patients or a small panel of autoantibodies. We report the analysis of 20 autoantibodies in 116 women with implants and 134 controls. The patients ranged from 26- to 66-years-old, with a mean of 45.7 +/- 8.3 years; breast prostheses were in place for a mean of 15 +/- 5.6 years, with a range of 4 to 30, the chief complaints of the 116 patients included polyarthralgias, fatigue, myalgias, morning stiffness, and decreased memory. All 250 sera were tested blindly using a panel of 20 autoantigens including SS-A, SS-B, RNP, cardiolipin (CL), collagen types I, II and IV, phosphatidylserine (PS), myeloperoxidase (MPO), sulfatides (sulf), thyroglobulin (TG), gangliosides (GDIa;GM2), proteinase-3 (PR3), Jo-1, Sm, HPRPP-ribosomal phosphate, histones (H2AH2B), Scl-70 and glomerular basement membrane (NC-1). Values from individual patients were considered positive only when greater than 3 SD above the control mean. There was a statistically significant greater frequency of autoantibodies in women with implants for 15 of the 20 autoantigens; these were particularly striking for anti-H2AH2B, HPRPP, SS-A, SS-B, Scl-70, CL, PS, GM2, and NC-1. Many patients harbored several autoantibodies; 20% had four autoantibodies; 8% had six autoantibodies. The association of autoantibodies and implants suggests an adjuvant action of silicon/silicone byproducts.