The comparative study of the human tumor cell line HEp-2 and rat liver for the detection of antinuclear and antinucleolar autoantibodies by the indirect immunofluorescence technic in routine screening test demonstrate that, taking titer and staining pattern into account, both substrates are able to separate autoimmune disease (systemic lupus erythematosus, rheumatoid arthritis, scleroderma and primary biliary cirrhosis) patients from healthy subjects. The minimal screening test must include sera diluted 1:20 and 1:80. The capability of the HEp-2 substrate to reveal and to discriminate different speckled nuclear and nucleolar patterns explain its greater performance, notably in detecting anticentromere antibodies highly specific for the CREST syndrome and a speckled nuclear antibody frequently associated with primary biliary cirrhosis, allowing an earlier diagnosis of autoimmune diseases presenting these patterns.