A case of delayed hemolytic transfusion reaction (DHTR) caused by blood transfusions after open heart surgery was reported in a 61-year-old woman. She had undergone mitral annuloplasty 8 years before. She underwent the 2nd mitral and tricuspid annuloplasty for recurrent mitral and tricuspid regurgitation in 1988. After the reoperation, she developed severe hemolytic anemia with fever. The anti-Jka antibody was detected in her serum by the blood antibody screening test. She was diagnosed to have a DHTR. She was treated conservatively and recovered.