Autoimmune hemolytic anemia (AIHA) was detected in pigs affected by spontaneous eperythrozoonosis. Autoantibodies against red cells were found by hemagglutination and hemolysin tests and direct and indirect antiglobulin tests using immunofluorescence. According to these findings and morphological results, the process in porcine eperythrozoonosis is to be classified as acquired autoimmune hemolytic anemia due to "cold" antibodies.