Hematopoietic growth factors comprise a family of hematopoietic regulators with biologic specificities defined by their ability to support proliferation and differentiation of blood cells of different lineages. The biologic specificities of these factors are highly complex, dose dependent, and frequently overlapping. Recent advances in the cloning of hematopoietic growth factor genes and the availability of recombinant material have led investigators to conduct clinical trials with these agents. Some of these factors have been studied and used in chemotherapy-induced neutropenia, myelodysplastic syndromes, and bone marrow failure syndromes. In this paper, we review the experience with growth factors that have been tested and that currently are being introduced in clinical trials. In addition, we report some factors with possible future interest for clinicians and researchers.