Provided herein are methods for the treatment of anemia, wherein the methods comprise administration of antagonists of Growth differentiation factor 11 (GDFl 1； also known as bone morphogenetic protein 11 (BMP11)) to a subject in need of the treatment. Antagonists of GDF-11 include anti-GDF11 antibodies, mutated extracellular domains of ActRIIA and ActRIIB having increased affinity to GDF11 compared to Activin A and ActRIIA-Fc fusion proteins. The present invention relates to the use of the GDF11 antagonist which is an extracellular domain of ActRIIA mutated to have higher affinity to GDF11 over Activin A for the treatment of beta thalassemia.
