Autism is one of the most serious childhood diseases that hinder development. The child is hardly autonomous. Limp in emotionally: often has too many emotions, or not enough. Intelligence is not reached, only that it can not serve because of its closure to the outside world. Can become competent in areas where features. Increases dizamonic, parts of his personality remain underdeveloped, while others exceed normal. Arguably keeps most of his life a certain fragility of nature and that needs to be supported by an environment to understand it and accept it. Access to education has made it possible for every child, for every person with autism in the family and in kindergarten, in school, in social groups in the local community. ABA (Applied Behavioral Analysis) is lately the answer to the autism problems and based on the classical behavioral therapies. This theraphy proves that changing certain conditions in the environment you can change the behavior of the children accordingly. In order to teach abilities, proper behavior and knowledge, all tasks are devided into small steps that are permanently monitorised and strongly reinforced untill we reach teaching more complex and suitable behavior to the age and potential of the children. Discrete trial is a three-part teaching unit that ABA is based on. It is a specific behavioral sequence used to maximize learning: Discriminative Stimulus ( request ), Response, Reinforcing Stimulus (consequence of the response).