Vascular abnormalities are frequent in connective tissue disease. In this kind of patients a lot of autoantibodies are observed. To screen them a strategy must be selected according to the connective tissue disease that is suspected. When the diagnosis is unknown the tests must screen a great number of autoantibodies and this is the case for indirect immunofluorescence assays, at the opposite when the diagnosis is known antibodies specific for the disease should be screened. Some antibodies are specific for a disease this is the case for antibodies directed against double stranded DNA, centromere, extractable nuclear antigens Sm, RNP, Scl-70, Pm-Scl, Jo1, neutrophil cytoplasmic antigen proteinase 3, and beta 2-glycoprotein I the cofactor of anti-cardiolipin antibodies. Anti-SS-A(Ro) antibodies are very frequent in autoimmune diseases and they are not specific for anyone of them. Some autoantibodies are frequent in autoimmune and also in non autoimmune diseases and this is the case for antibodies directed against phospholipids, single stranded DNA, histones, rheumatoid factor. The detection of antibodies depends on the assays used for screening, that is why results should mention the assay used for their detection. The standardization of the detection of the autoantibodies especially when quantitative results are requested, is not yet performed enough. So to obtain reproducible results when monitoring a patient the screening must be done by the same assay in the same laboratory.