Myelodysplastic syndrome is a closely related group of acquired bone marrow disorders characterized by ineffective and dysplastic hematopoiesis. These clonal disorders frequently progress to acute leukemia. Acute myelomonocytic leukemia with eosinophilia is characterized by an increase in abnormal eosinophils in the bone marrow, relatively good clinical course and inv (16) chromosomal abnormality. We experienced one case of refractory anemia with excess blasts which progressed to refractory anemia with excess blasts in transformation and finally to acute myelomonocytic leukemia with eosinophilia showing peculiar chromosomal abnormalities of der (1;7).