The thalassemia syndromes are a heterogeneous group of inherited anemiascharacterized by defects in the synthesis of one or more of the globin chainsubunits of the hemoglobin tetramer. Clinical manifestations are diverse,ranging from asymptomatic hypochromia and microcytosis to profoundanemia, which can be fatal in utero or in early childhood if untreated.Palliative treatment of the severe forms by blood transfusion is eventuallydefeated by the concomitant problems of iron overload, alloimmunization,and blood-borne infections. The excellent results of bone marrowtransplantation in young patients with thalassemia who have yet toaccumulate excessive iron or who have successfully controlled iron storeshave made transplantation an important consideration in their management.The major problem facing hematopoietic stem cells transplantation inthalassemia patients is graft-versus-host disease. Although the overallprobability of survival for patients with thalassemia was 100%, disease-freesurvival was only 79%. Hematopoietic stem cells transplantation should beaddressed in terms of currently identified risks and benefits, the likelihood offuture improvements, and the potential for new treatments such as genetherapy. The use of genetics and genetic manipulation by humans for thetherapy of human disease is a new and rapidly evolving field of both basicscience and clinical medicine. The major limitation to progress in genetransfer at this point lies with the vectors, which have a series ofshortcomings that have limited successful application.