Autism refers to a complex group of neurodevelopmental disorders that influence the normal development of brain in terms of social interaction, communication skills and cognitive functions. The lack of a single biological pattern of symptoms and clinical aspects of the disorder, hinder the ability to make a diagnosis and prescribe the appropriate therapy. Beginning with the initial psychological theories and theses that autism is caused by abnormal psychological interactions within the family, the research during the past decades affirmed the role of a strong genetic influence and interaction with environmental factors in developing the disorder. Starting with a short insight into the neuropathological changes and regions of the brain affected by autism, followed by a neurotransmitter overview and their involvement in the etiology of autism as well as an introduction to the developmental psychopathology of autism while putting a particular emphasis on endophenotypes, and lastly, a genetic and epigenetic approach, this bachelor’s thesis presents the overview of key discoveries and current understanding of autism spectrum disorders. Pathogenesis of neurodevelopmental disorders including autism is still inconclusive and therefore, further research along with more readily available modern techniques should include the interdisciplinary approach which will enable a further progress towards the discovery of the biological basis of the disorder.