The immunofluorescence test on paraformaldehyde-fixed cells was used for the detection of antibodies bound to the platelets and granulocytes and present in the sera of 24 patients with Evans syndrome and a further 29 patients with both idiopathic thrombocytopenia (ITP) and idiopathic neutropenia (INP), but without autoimmune haemolytic anaemia (AIHA). The direct immunofluorescence test on platelets and/or on granulocytes was positive in all patients with a cytopenia, but the sera of only 17 patients with the Evans syndrome and 15 of the other patients contained platelet- or granulocyte-specific autoantibodies. From absorption and elution experiments, it appeared that the autoantibodies were directed against antigens specific for the various peripheral blood cells, i.e. erythrocytes, platelets and granulocytes and that they were not cross-reacting.