Over the last decade, the key role of specific glycoproteins (hematopoietic growth factors) in the proliferation and maturation of hematopoietic cells (in conjunction with some of their particular functional activities) has been demonstrated through in vitro and in vivo studies. These glycoproteins have been evaluated for their potential application in reducing the duration of myelosuppression following conventional chemotherapy and autologous bone marrow transplantation. Preliminary results using granulocyte-macrophage colony-stimulating factor to restore neutrophil competence seem to be encouraging.