Ultrastructure varities in erythroid line of 6 patients with Thalassemia were studied by electron microscopy. A number of electron-dense inclusions (alpha or beta chains precipitation) were noted in cytoplasm or nuclei of polychromatic erythroblasts, normoblasts, reticulocytes and erythrocytes. The nuclear membranes showed absence or duplication and the space between two layers of nuclear membranes dilated. Autophage vacuoles and vacuolation were easily observed within the early and late stages of erythroid series. The figure of red cells was markedly abnormal, the characteristic ropalocytes might be found. In addition, the various forms of squeezed and partly destructed RBC which had been sequestrated in the minute sinuses of spleen were observed. The observations above provide direct morpdological evidences of the pathogenesis in Thalassemia