Antinuclear antibodies, also referred to as ANA, is a test that is often required for rheumatologic screening and is performed on every patient suspected of having a rheumatic disease. For laboratory quality control reasons, an ANA of more than 1:100 is considered positive (its normal value is related to the test reagent and the test method). Its titers are, from low to high, 1:100, 1:320, 1:1000, and 1:3200; the higher the titer, the greater the likelihood of rheumatic disease. ANA positivity does not mean that rheumatism is definitely present, and other tests are needed to clarify the cause.ANA positivity can be found in healthy people, with a rate of about 3% to 19%, but most often at low levels, such as 1:100 or 1:320, and may also be found in patients with tumors. When autoantibodies are detected in tumors, the first consideration is that they are caused by the tumor itself and not by the rheumatic disease. Therefore, the clinical significance of antinuclear antibody 1:320 needs to be considered in the context of the specific disease.