Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 4 1 2005 03 15 1 8 Susanna M. Müller Wilhelm Friedrich 2015 10 01 Primary Immunodeficiencies constitute a group of highly complex congenital disorders most of which are characterized by a very poor prognosis. Allogeneic hematopoietic stem cell transplantation (HSCT) has become an established curative treatment approach in many of these disorders, which may be permanently corrected. In this presentation basic and practical aspects of HSCT are presented, with an emphasis on its application in lymphocyte disorders such as severe combined immunodeficiency (SCID). Optimal results and outcome of HSCT are highly dependant on early and correct diagnosis of these rare disorders, and HSCT should usually be applied early in the course of the disease in order to prevent irreversible complications from infections. Clinical results will be summarized based on recent analysis performed in large patient cohorts, which have shown steady improvements and have led to a marked change in the prognosis of patients with primary immunodeficiencies. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/92 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/92/92