Taking into consideration the INSETs’ direct influence on teachers’ professional development and indirect influence on the education, the present study aims to determine teachers’ opinions about in -service training activities and their proposed solutions to improve the effectiveness of the in-service training activities via the semi- structured and in-depth interviews. Also this paper specifically analyzes the latest statistics of in-service trainings in Turkey with holistic and critical approach. Data were collected from 59 teachers from three different types of school (primary, secondary, junior high school) in Turkey through a semi-structured interview, and analyzed through content analysis by searching for patterns and synthesizing them. The transcriptions were coded through NVivo 8 and then grouped together to derive broader themes shaped around core meanings (Miles & Huberman, 1994). While the most useful aspects of in-service training programs are found as professional development, meeting new people and professional development, weaknesses of in-service training programs are poor planning, lack of qualified trainers and lack of practical implications according to teacher opinions. Teachers suggested that employing expert trainers, effective planning and more interactive contents are crucial for an ideal INSET activity. The study concludes with possible reasons for the problems in concern, and practical implications.