Case of hematological disorders associated with acute myocardial infarction had been found in five of forty five autopsy cases which had hematological disorders during the past seven years. The five cases of hematological disorders consisted of two cases of myelodysplastic syndrome, a case of aplastic anemia, a case of primary myelofibrosis in blast transformation, and a case of acute myelogenous leukemia. All the patients were over 60 years old. Four patients had coronary artery stenosis and extensive myocardial infarction. Fibrinogen degradation products were elevated in four patients. DIC was recognized in two and suspected in two others. In all cases, platelet counts markedly decreased to less than 2.5 x 10(10)/L. Since no chest pain was noted by any patient, it was difficult to diagnose acute myocardial infarction without autopsy, except in one case. It is important to recognize the possibility of severe cardiac dysfunction due to myocardial infarction in thrombocytopenia, especially in the aged with DIC.