Hematopoietic stem cell transplantation (HSCT) has been one of the revolutionary discoveries in the world of science leading to cure of many of the hematological malignancies and for several nonmalignant conditions. It involves harvesting of stem cells from either the bone marrow most traditionally, peripheral blood or umbilical cord and then transplanting them into a recipient. This could be either allogeneic i.e. from another donor or autologous i.e. from the patient himself. The first successful series of autologous HSCT for lymphoma was reported in 1978. With a better understanding of immunological mechanisms and molecular sciences, it has now been possible to decrease the rates of rejection due to incompatibility thereby improving overall graft survival many fold. Today, more than 50.000 transplants are carried out annually worldwide and the numbers are increasing each year.