The neurotrophic factors are proteins that enhance neuronal survival, differentiation, neurotransmitter function and resistance to neurotoxins and lesion. For these reasons the neurotrophic factors are considered as a new potential therapeutic tool for the treatment of neurodegenerative disorders, a group of diseases that produce the most important cause for disability in the Western world. Neurotrophic factors are used in vitro and in vivo models of neurodegenerative disorders. In this context the results of the treatment with neurotrophic factors is very reassuring. Several neurotrophic factors reached the stage of investigation in primate models of neurological disorders and some of them have been used in humans with these diseases. The results so far obtained in humans have been disappointing for several reasons including technical problems for delivery, unbearable side effects or lack of efficacy. Future approaches for the use of neurotrophic factors in humans should include the following: 1. Testing of the putative compounds in animal models more related to the pathophysiology of each disease, such as genetic models of neurodegenerative diseases. 2. New methods of delivery, including genetic engineering by viral vectors and administration through implantation devices. 3. Better methods of testing, including the novel neuroimaging techniques.