A 65-year-old woman was diagnosed with Coombs-positive autoimmune hemolytic anemia (AIHA) and pure red cell aplasia (PRCA) in May 1992. One month later, her PRCA went into remission following treatment but she developed idiopathic thrombocytopenic purpura and was diagnosed with Evans syndrome. Although her condition resolved with administration of prednisolone and azathioprine, it was necessary to continue treatment with gradual tapering over the following two decades. In October 2012, her hemolytic anemia again worsened, and lymph node swelling, splenomegaly and B symptoms developed. She was diagnosed as having diffuse large B-cell lymphoma (DLBCL) based on lymph node biopsy. However, AIHA was not considered to be the cause of her hemolytic anemia, but rather to be related to DLBCL. This was because a Coombs test and other extensive investigations for Coombs negative-AIHA yielded negative results. The patient underwent CHOP therapy, and all of her symptoms improved. Herein, we report this rare case in which DLBCL developed after the onset of Evans syndrome.