The recent cloning of new members of the nerve growth factor (NGF) family, namely brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), as well as the ciliary neurotrophic factor (CNTF) has greatly expanded our knowledge of the structural properties and neurotrophic activities of these proteins. Elucidation of their developmental and topographical expression and associated receptors in both the central nervous system (CNS) and peripheral nervous system (PNS) is proceeding at a brisk pace, leading us to propose a potential pharmacological use of these proteins. This possibility will ultimately rely upon a more complete understanding of the roles of these trophic factors in nervous system physiology and pathology.