The choice of treatment strategy for patients with simultaneous cardiac and malignant diseases is often debatable. We report 11 patients with simultaneous cardiac and malignant diseases who were hospitalized in our institution over the past 6 years. The patients were 9 males and 2 females with a mean age of 71.9±9.0 years old. There were 7 cases of ischemic heart disease( IHD), and 4 cases of valvular disease. Malignant diseases consisted of 4 cases of colon cancer, 2 cases of pulmonary cancer, 2 cases of hepatic cancer, and 1 case each of sigmoid colon cancer with liver metastasis, gallbladder cancer, and pancreatic cancer. Eight of the 11 cases(73%)were hospitalized because of a symptom associated with cardiac disease, and malignant disease was diagnosed incidentally during examination or treatment. Four of the IHD cases preceded coronary revascularization by off-pump coronary artery bypass grafting (OPCAB) or percutaneous coronary intervention (PCI). Two of the valvular cases and 2 of the IHD cases underwent cardiac surgery after treatment of malignant diseases. In 3 cases, only 1 of the diseases was treated. Seven cases died of malignant diseases at the present. The choice of treatment strategy should be established for patients with simultaneous cardiac and malignant diseases in consideration of the severity of the cardiac disease and the expected prognosis of the malignant disease because there is no standardized method of treatment.