[Serologic data from 537 patients with a positive direct Coombs' test (Vienna 1949 to 1979)].

In the period from 1949--1979 537 patients with positive direct Coombs-reaction were observed, their serological findings are presented and analysed regarding correlations to ABO, Rh, age and sex. Close connexions between the strength of the direct Coombs-reaction, autoantibodies in the serum and the absence of haptoglobin were found as it was expected. The sensitivity of different methods to detect autoantibodies, frequencies and specificities are discussed. Two causes of autoimmune hemolytic anemia with monospecific autoantibodies and four healthy blood donors with unexpected and inexplicable positive direct Coombs-reaction are described.