A 14-month-old boy was referred to our hospital for evaluation of severe anemia. In the bone marrow aspiration smear, normal cellularity with severe erythroblastopenia (3%) was observed. The hemoglobin electrophoresis of the patient and his father were compatible with the b-thalassemia trait. Because macrocytosis of DiamondBlackfan anemia (DBA) is masked by microcytosis of b-thalassemia trait, the diagnosis of DBA co-existing with b-thalassemia trait might be challenging. We report herein a case of DBA co-existing with b-thalassemia trait in a Turkish boy. Am.