The year 2007 marks the 50th anniversary of the identification of antibodies to double-stranded (ds) DNA. Whilst widely regarded as synonymous with patients who have systemic lupus erythematosus (SLE), doubts have been raised about their significance and the extent to which they are genuinely part of the pathogenesis of the disease rather than being mere bystanders. Problems with assays used to detect them are still evident but they remain widely utilized both to help establish the diagnosis of SLE and to monitor the progress of the disease. This review explores each of these aspects and concludes that whilst some way short of ideal, their measurement remains a useful criterion for the disease and some of these antibodies do appear to be genuinely pathogenic. However, further research is needed to establish beyond 'reasonable doubt' whether they are merely part of the spectrum of anti-nucleosome antibodies, the precise mechanisms by which they 'exert' their pathogenic effects and to what extent blocking them would be a useful therapeutic goal.