A 44-year-old previously healthy male was diagnosed as anemic and treated at a nearby hospital. A year later, he was admitted to our hospital for precise examination of the progression of refractory anemia. Blood examination showed hemolytic anemia and more detailed examination of this hemolysis revealed pyruvate kinase deficiency. The activity was 15.1% of a normal control. Pyruvate kinase activities of his family members were normal or slightly decreased. Ten months after admission to our hospital, 2% of blast cells with Auer's body in the peripheral blood were noted which increased progressively. The bone marrow contained 17.3% of blast cells with a subsequent diagnosis of acute myelogenous leukemia being made. Although intensive chemotherapy was performed, the patient achieved a brief remission and died 2 years after admission to our hospital.