Recent research advances in neuroscience show that neurotrophic factors are proteins that affect selectively various kinds of neurons of CNS and PNS. Brain derived neurotrophic factor (BDNF) is another neurotrophic factor that was first reported by Barde, a German chemist, thirty years later after the nerve growth factor had been found out. BDNF plays an important role in the growth, development, differentiation, maintenance and regeneration of various types of neurons in the CNS and has potential application to the treatment of brain injury and neurodegenerative diseases such as Alzheimer's disease, Parkinson's syndrome, Huntington's chorea and amyotrophic lateral sclerosis. In this paper, the structure, function and potential clinical application of BDNF were reviewed.