To determine whether different assays of antidouble stranded DNA (anti-dsDNA) antibodies provide comparable information in quantitative antibody assessment over time, longitudinal correlations between 3 anti-dsDNA antibody methods were derived. Determinations of anti-dsDNA antibody levels on serial samples from 9 patients with systemic lupus erythematosus (SLE) were performed by filter binding radioimmunoassay, enzyme linked immunosorbent assay, and Crithidia indirect immunofluorescence. Substantial pairwise correlations among assay methods were found (r = 0.544 to 0.804; p less than 0.001). In addition, anti-dsDNA antibody levels as measured by each assay were inversely correlated with levels of the 3rd component of complement. Our results indicate that changes in antibody levels as determined by these 3 methods closely parallel each other over time, and suggest that the array of anti-dsDNA antibodies detected in patient sera remains relatively constant over time.