In this research, the opinions of teachers, who have received in-service trainings on the subject of information technologies, on their levels of use of information technologies in classes are investigated. A total of 164 teachers, who were working in the city of Sakarya in the 2007-2008 Academic Year, have participated in the research. A questionnaire has been administered to all of these teachers in order for them to evaluate the in-service trainings they had participated, and semi-structured interviews have been conducted with 45 of them. After the research, it has been observed that those teachers who have received in-service trainings on information technologies use information technologies in their classes, the levels of use of information technologies are higher among those teachers who are satisfied with the in-service trainings than those who are not, the problems that teachers encounter while using information technologies mostly stem from equipments, and schools that do not have any problems in terms of equipment lack internet connection and educational software.