Considering the recent rapid developments in science and technology, it is quite important for individuals to be able to make decisions about their own future and their children's future for the society in which they live and to know how to establish a balance of risk and decision. For this reason, teacher training programs should be planned to internalize pre-service teachers' awareness of responsibility. Regarding this point, the development of pre-service science teachers' bioethical values was examined on a class level basis using survey research. Research sample consisted total of 286 pre-service teachers of Science Teacher Training Program. Bioethical Values Questionnaire was applied to determine pre-service teachers' bioethical values. As a result of analyses, it was determined that pre-service teachers' bioethical values increased according to their class levels they attended. It was stated that pre-service science teachers' bioethical values related to sub-dimensions of "Benefits of Biotechnology Applications", "Science and Ethics", "Reproductive Technologies and Cloning" and "Control of Genetic Interventions" were increased based on participants' class levels. In addition, the results of the study revealed that pre-service teachers also had some concerns about the benefits of biotechnology applications.