Autologous hematopoietic stem cell transplantation (HCT) is a procedure used to treat and/or cure a number of malignant conditions including lymphoma and myeloma. Briefly, following collection and cryopreservation of hematopoietic stem cells, very high doses of chemotherapy to overcome tumor resistance are given followed by reinfusion of the collected hematopoietic stem cells. The transplanted HSC reconstitute the marrow and restore normal blood cell production and reconstitute the immune system. More recently, autologous HCT has been shown to be an effective treatment in a number of autoimmune disorders such as multiple sclerosis, scleroderma, and CD. For autoimmune disorders, the presumptive mechanism of action is that intensive immunoablation followed by reinfusion of hematopoietic cells results in an immunological "reset" without recurrence of the autoimmune disease. The most common chemotherapy regimen used for autoimmune disorders is a combination of cyclophosphamide with anti-thymocyte globulin. The safety of this regimen is well established and has been recommended for the previously mentioned conditions by the European Group for Blood and Marrow Transplantation (EBMT).