Acquired aplastic anemia (AA) is a rare and potentially fatal disease which is characterized by pancytopenia and a hypocellular
bone marrow. Hematopoietic failure is the result of immune-mediated destruction of both the bone marrow
stem and progenitor cells in most patients. Currently more than 85 % AA patients becoming long-term survivors if diagnosed
and treated appropriately. HLA (human leucocyte antigen) identical sibling hematopoietic stem-cell transplantation
(HSCT) is the treatment of choice in younger patients, whereas immunosuppressive therapy (IST) is often used in
older patients or in those who lack a sibling donor. The improvement in outcome of HSCT and IST is probably due to improved
transplant protocols and supportive care. HSCT from unrelated donor is indicated for patients who failed at least
one course of IST. Efforts are currently underway to both improve IST regimens and to expand the application of HSCT.