The aim of this study is to evaluate the course supervision practices of high school principals according to the opinions of the field teachers who take courses in high schools. For this purpose, an interview was conducted with randomly selected 50 teachers who were working in 9 high schools in Siirt city center. The research is a descriptive research designed with qualitative method. To collect detailed data from teachers, interviews were conducted using structured interview form. The questions of the structured interview form were prepared based on the literature and the current practices and arranged in the preliminary interviews with the teachers and school administrators. The questions in the form are revised by the academicians who are experts in the field. The data were analyzed by content analysis technique and expressed as tables. In terms of course supervision, the majority of teachers (from 50 different views, 23 yes, 11 partly yes) found the course supervision as suitable for academic purposes with the condition that it should be conducted with competent people. However, approximately one third of the teachers (N:50, f:14) stated that it was not appropriate to observe within the scope of the course supervision due to supervisory incapability, the use of the control as pressure, the violation of the privacy of the classroom environment, the lack of supervision, and the fact that supervision is seen as an indicator of distrust to the teacher.