The use of the recombinant hematopoietic growth factors G-CSF and GM-CSF have shortened the period of neutropenia, or avoided this problem, in many cancer patients who have received cytotoxic therapy. Although these benefits have been particularly striking in the autologous bone marrow and/or autologous peripheral blood progenitor cell transplant setting, most data suggest that the use of G-CSF and GM-CSF only marginally enhance recovery of the neutrophil count when administered after allogeneic bone marrow infusion. Furthermore, in the allograft setting these expensive agents have not provided benefit in the form of enhanced platelet count recovery, lessening the incidence of graft-versus-host disease, or improvement in overall survival. These data do not justify routine widespread use of G-CSF and GM-CSF and suggest that these agents should be reserved for patients who experience delay in engraftment after allogeneic bone marrow infusion. Administration of erythropoietin, on the other hand, may reduce the need for homologous red blood cell transfusions, and may increase the safety margin for both the allogeneic bone marrow recipient and as well as the donor. Recombinant hematopoietic growth factors targetted specifically to enhance platelet recovery after transplantation (such as interleukin-3, interleukin-6, and interleukin-11) have shown promise after autotransplantation and after conventional dose chemotherapy, and likely will be evaluated in the allogeneic transplant patient.