Purpose to assess the knowledge of teachers in elementary education about the communication of people with autism spectrum disorders at two different times, pre and post-intervention. Methods it was a comparative and descriptive study, involving 160 teachers from municipal elementary school of both genders, aged between 23 and 65. To check the teachers’ knowledge of communication in autism spectrum disorders, a specific questionnaire for this study was developed and applied. It was offered to teachers and administered at two different times, pre and post-intervention. The intervention procedure consisted of two meetings of four hours each, conducted by speech therapist and the delivery of a guidance manual on the autism spectrum disorders, emphasizing the aspects of communication and language. The responses pre-and post-intervention were analyzed and compared. The results were treated statistically (p <0.05 and in some cases p <0.01, the chi-square test for proportions was used). Results it was observed that the teachers had a limited knowledge and inadequate communication about the autism spectrum disorders and on these clinical cases in general. In addition, there was significant increase of correct answers by the teachers after the intervention. Conclusion there is a restricted teachers’ knowledge of communication in autism spectrum disorders and positive effects after the intervention procedures, through the analysis of the pre and post-intervention phases, which showed a significant increase in appropriate responses on the autism spectrum disorders.