Autoimmune hemolytic anemia (AIHI) is an infrequent disease in the pediatric age group. Its diagnosis is given by the direct antiglobulin test (DAT) or Coombs' test, which determines which type of globulin (IgG or complement) is the cause of the hemolysis. The type of globulin involved determines the etiology of AIHI, which is usually confirmed by positive results of other laboratory investigations such as cold agglutinin determination or the Donath-Landsteiner test. We present three cases of AIHI. DAT was positive to complement with diverse etiology: warm antibody with IgG-negative DAT, cold agglutinins associated with infectious mononucleosis, and Doth-Landsteiner antibodies. In all patients, empirical treatment with corticosteroids was initiated. The treatment was withdrawn or continued, depending on the final etiology of AIHI.