The impact of autoimmune diseases is growing from both a clinical and a laboratory point of view. Diagnostic assays are now being transferred from dedicated specialised laboratories into high-throughput service laboratories. The increasing number of available methods has raised the variability among the laboratories, making their reproducibility a critical problem. On the other hand, reliable tests are needed for early diagnosis and prompt treatment, and the cost of repeated confirmatory tests should be reduced and unnecessary further investigations avoided. New methodologies, particularly for antinuclear antibodies (ANAs), have been applied to autoantibody detection in order to screen and process larger volumes of clinical specimens more quickly and at less cost than the traditional methods. However, because of the lack of their sensitivity to detect all ANAs and standardisation, inaccuracies (including false positives and negatives) in the results have been reported. A committee of the American College of Rheumatology was formed to address this issue. Specific recommendations have been suggested that represent a realistic first step in the standardisation of diagnostic tests for autoimmune diseases.