Considering the specificities of the autistic student and the perception of a significant increase in the number of enrolled in Basic Education, the present study was permeated around the following general objective: to investigate teachers' conceptions about the autistic student and practices in Mathematics Teaching possibly directed by these conceptions. The research approach, of the qualitative type, used as a procedure for data production semi-structured interviews, applied to eight teachers who teach Mathematics in classes where, among the students, there are autistics. For data analysis, some elements of Content Analysis were considered. From the defined categories, it was possible to conclude that: a) the practices with autistic students are different from the practices developed with the other students; b) in the conception of the research subjects, the inclusion of the autistic student proves to be a challenge for those involved in this journey; c) the lack of initial and continuous training and the inexperience with autistic people inside and outside the school context makes knowledge about autism even more precarious and, because of that, the teacher's role as a mediator in the inclusion process becomes limited; d) there is a need for structural support so that the teaching practice with autistic students happens in a more appropriate way; e) Mathematics is a discipline that favors the teaching and learning of the autistic, when approached from practical methodologies, with themes focused on the daily lives of these students; and f) there are valuations about the use of digital technologies in practices with autistic students.