This study was carried out in order to determine the functionality of the Professional Development Training Seminars, which were held at the beginning and end of each academic year in the institutions affiliated to the Ministry of National Education and lasted approximately one month. This research; A qualitative study, a case study technique was used in the study. Since the study was conducted with teachers working in different types of schools, the study used holistic multi-state design from case study technique designs. The study group consisted of 20 teachers who are working in primary and secondary schools and high schools affiliated to the Ministry of National Education in the central districts of Antalya in the 2018-2019 academic year. In the research, semi-structured interview form consisting of open-ended questions was used as data collection tool and the answers of the participants were recorded on the voice recorder. The research data were analyzed using NVIVO 12 computer software after transcript processing. Frequency and percentage analysis were used as part of the content analysis. The participant's opinions were categorized into draft themes under main themes and sub-themes and finalized by expert opinion. The sub-themes formed as a result of this theme are also included in the findings in the form of tables according to their frequency. In addition, these themes were supported by direct quotations from the participants and the credibility of the research was increased. As a result of the research, the main finding is that participants' professional development training seminars are not as functional as they are practiced. According to the findings of the study, participants approached professional development seminars from two different perspectives. First, the participants considered these seminars as a positive, contributing and productive process in terms of preparation for education, planning, period evaluation, individual and professional development, cooperation, exchange of information, examination of course materials, being aware of changes in education system. But in another aspect, the participants considered these seminars as Formality, Time Loss, Money Waste, Drudgery, Empty Process, Meeting, Board, Commission, Gossip, Documentary.