The aim of this study is to examine the application process of preservice primary school teachers in primary schools within the scope of teaching practice course. In addition, the aim of this study is to evaluate the preservice teachers' mathematics teaching competencies by the practice teachers in their schools. For the purpose of the study, semi-structured interview technique was used from qualitative research methods. The sample of the study was composed of 17 primary teachers assigned as practice teachers in the school they study. The data were collected through semi-structured interviews with these teachers. As a data collection Tool, the interview form prepared by the researcher, which includes questions about the application process and Mathematics teaching competencies of the pre-service teachers who continue to practice throughout the semester was used. According to the findings, although the level of professional knowledge of the preservice teachers was generally good, it was not seen that they were sufficient in professional skills because of being inexperienced. The situations were the same specifically in the level of professional knowledge and skills in mathematics teaching. It was stated that pre-service teachers were generally willing to come prepared for the course and to prepare in cooperation with the teacher. It was stated that pre-service teachers had a positive relationship with students in the classroom, but discipline problems could arise when students felt it especially when the preservice teachers were unprepared.