Among the most important tasks of education in information societies is to train individuals who can think universally, query the information and work cooperatively. Teachers, who will train these individuals, should also improve themselves according to these qualities as well as the needs of the time. Well-planned in-service trainings would be the most effective way of updating the knowledge and skills of the teachers on the job according to the conditions of our age. The aim of this research is to investigate the teachers’ in-service training needs who are working in Bilecik province. 1632 teachers replied the questionnaire and open-ended questions prepared by the researchers online. In the first part of the questionnaire, demographic information was asked and in the second part consisting of 38 questions in 5-likert type, the professional development, cooperative study and communication, innovative training, evaluation and assessment, guidance, classroom management and leadership skill perceptions of the teachers were tried to be examined. Teachers’ competency levels of information and communication technologies and at the same time, difficulty levels they have in using the information and communication technologies in educational settings are asked in the third part of the questionnaire. In the final part of the data collection tool, teachers were asked their suggestions for more efficient in-service trainings and fields of trainings other than the stated ones they want to take. The findings of the research, the questionnaire data of which were analyzed with quantitative analysis techniques and the open- ended questions with qualitative analysis techniques, showed that teachers see themselves less competent in technology whereas more competent in the other fields. Teachers provided suggestions about the time of the trainings as well as the qualities of the trainers and the content and benefits of the trainings. Teachers especially requested trainings that would provide themselves with technological competency.