Non-myeloablative allogeneic peripheral blood stem cell transplants are currently being investigated for engraftment efficacy and toxicity in a number of transplant centers. Preliminary data including our own experience with 13 patients undergoing this type of procedure have shown a high rate of complete donor engraftment, low toxicity, and preservation of the GVL effect. Two recent published studies investigating non-myeloablative allo-transplantation in standard risk patients revealed an extremely low rate of transplant related complications and mortality.