Abstract A dot immunobinding assay procedure has been developed for autoantibodies, and has been applied to the sera of MRL lpr/lpr mice. The profiles thus obtained include assays for circulating immune complexes, and antibodies against single-stranded DNA, double-stranded DNA, ribosomes, soluble nuclear deoxyribonucleoprotein, and retroviral antigens. Part of the data was compared with ELISA results. The anti-DNA assays were specific, as some individual sera show exclusively anti-double-stranded DNA specificity. The finding of anti-ribosomal antibodies in these mice extended the analogy between the murine disease and human systemic lupus erythematosus. The specificity of the anti-retroviral antibodies was examined following electrophoretic separation of the antigens and blotting on nitrocellulose. Previously undescribed classes of anti-retroviral antibodies were found. Circulating anti-retroviral protein p30 was found in all sera having high anti-retroviral titers.