We describe an enzyme-linked immunosorbent assay (ELISA) with adsorption of histones (total and fractions) on glass beads and saturation of excess sites with sheep serum. The anti-histone antibodies are detected with peroxidase conjugate and developed with Trinder's reagent which has great stability. This very sensitive method detects anti-histone antibodies in 53% of SLE patients and in virtually no other diseases. Positive reactions are observed only with total histones and fractions H1 and H2b.