With the identification and recombinant production of the hematopoietic growth factors, these cytokines have been evaluated in the treatment of primary bone marrow failure states and after myelosuppressive chemotherapy or radiotherapy. A lot of clinical trials with hematopoietic factors have been performed in patients with haematologic and oncologic diseases within the last decade. Granulocyte colony-stimulating factor [G-CSF], granulocyte macrophage colony-stimulating factor [GM-CSF], interleukin-3, interleukin-2, erythropoietin and in phase I/II trials thrombopoietin [TPO] are available for the clinical use. At the present, there is a broad use of growth factors. Most studies have been done with G-CSF and GM-CSF, their beneficial effects are proven regarding improvement of hematopoietic recovery after chemotherapy. This results in a marked reduction of infectious risks and a shortening of drug- and radiation-induced myelosuppression. CSFs are most important in mobilizing peripheral blood progenitor cells [PBPC] and have allowed high dose therapy to be given to patients who would not have been able to undergo conventional bone marrow transplantation. However, an improved outcome and improved survival rates with standard chemotherapy protocols couldn't be documented by studies up to now, even though higher chemotherapy doses are possible by the use of hematopoietic factors.