A bone marrow examination in a young woman with anemia and β-thalassemia trait showed dyserythropoiesis in less than 10% of erythroblasts without other myelodysplastic changes, and cytogenetic analysis revealed trisomy of chromosome 8. Although she did not fulfill the current World Health Organization (WHO) criteria for diagnosis of a myelodysplastic syndrome, her acquired bone marrow disorder behaved as such, and she later developed acute myeloid leukemia.