The present prevalence of autism spectrum disorders (ASD) demands changes in health policies highlights barriers that are inherent to the national diversity and therefore poses great challenges to the planning and delivering specialized services. Systematic data regarding the level of knowledge and information about autism in the general population may help in building a set of evidences to support decision-making processes about intervention proposals directed towards this population. Aiming to contribute to evidence-based practice, this study used a digital-delivered questionnaire to assess the knowledge by the general population about autism in Brazil. A self-explanatory questionnaire was made available on-line. It was comprised by 57 questions divided in five domains: data about the answerer; information about how the person had access to the issue of autism; information about the concept of autism (signs, symptoms and etiology); information about the characteristics of persons with autism and what are the professionals that are essential in the team that assists these individuals. Participants were contacted via e-mail and given full information on the nature of the research. They were 4282 persons living in the five large regions of Brazil. Results indicate that most of the participants were mothers, followed by teachers. The analysis of the answers demands consideration of the hypothesis that although most of the participants have answered that they knew what is Autism, this knowledge is based on lay beliefs and not on scientific-based information. This reality must be taken into account when proposing intervention programs directed to persons with ASD.