Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family of survival-promoting molecules, plays a vital role in the growth, development, maintenance, and function of several neuronal systems. The purpose of this review is to document the support for the involvement of this molecule in the maintenance of normal cognitive, emotional functioning, and to outline recent developments in the content of Autism spectrum disorder (ASD). Current and future treatment development can be guided by developing understanding of this molecule's actions in the brain and the ways the expression of BDNF can be planned. Over the years, research findings suggested a critical role played by BDNF in the development of autism including increased serum concentrations of BDNF in children with autism and identification of different forms of BDNF in families of autistic individuals.