Fibroblast growth factor-2 is a member of a large family of proteins that bind heparin and heparan sulfate and modulate the function of a wide range of cell types. FGF-2 occurs in several isoforms resulting from alternative initiations of traslation: an 18 kDa cytoplasmic isoform and four larger molecular weight nuclear isoforms (22, 22.5, 24 and 34 kDa). It acts mainly through a paracrine/autocrine mechanism involving high affinity transmembrane receptors and heparan sulfate proteoglycan low affinity receptors. It is expressed mostly in tissues of mesoderm and neuroectoderm origin, and plays an important role in mesoderm induction, stimulates the growth and development of the new blood vessels (angiogenesis), normal wound healing and tissue development. FGF-2 positively regulates hematopoiesis by acting on various cellular targets: stromal cells, early and committed hematopoietic progenitors and possibly some mature blood cells. FGF-2 is a potent hematopoietic growth factor that is likely to play an important role in physiological and pathological hematopoiesis.