A 60-year-old man was admitted to our hospital with severe anemia and blood findings showed hemolytic anemia. Further serological examination revealed both warm-reactive autoantibody and cold agglutinin against erythrocytes. The cold agglutinin showed a low titer, 1 : 32 at 4 degrees C, and had a high thermal amplitude of 30 degrees C or higher, resulting in sufficient activity for hemolysis. Since no underlying disorders could be detected, the diagnosis was idiopathic mixed-type autoimmune hemolytic anemia. Although thrombocytopenia (Evans syndrome) subsequently appeared, corticosteroid was extremely effective for both anemia and thrombocytopenia. In this report we describe a rare case of Evans syndrome associated with mixed-type autoimmune hemolytic anemia, which had a dramatic response to corticosteroid therapy.