The present study was designed to study the possible role of the female sex hormone, estradiol in conjugation with DNA, in the pathogenesis of systemic lupus erythematosus (SLE). Calf thymus DNA fragments (average size 200 bp) were covalently linked to estradiol-albumin (E₂-BSA) by treatment with glutaraldehyde. The conjugate was separated from free DNA by gel exclusion chromatography. It was characterized by UV spectroscopy and thermal denaturation studies. The conjugate (E₂-BSA-DNA) induced high titer antibodies which were highly specific towards their immunogen. These antibodies also recognize estradiol-albumin and B-estradiol but not native DNA (B-form), brominated DNA (Z-form) or poly(rG).poly(dC) (A-form). The E₂-BSA-DNA conjugate showed significant binding with SLE sera known to have a high level of anti-native DNA antibodies. The results indicated the recognition of unique conformation of estradiol-BSA-DNA conjugate by naturally occurring SLE anti-DNA autoantibodies.