Öz Problem Statement: High-stakes examinations are critical turning points in the professional careers of student-teachers. Little is known; however, about the degree to which these examinations affect the educational practices of the student-teachers and their approach to their program. The present study attempts to analyze the washback effect of SEPPPO, a national high-stakes examination, on prospective English teachers.Purpose of Study: This paper reports on a research study in which washback effect of "The Selection Examination for Professional Posts in Public Organizations" (SEPPPO) in Turkey. The findings may illuminate the practice of the authorities who may make a possible modification in this examination in the future.Methods: In a mix-method design, the data were obtained from 164 student-teachers following a private SEPPPO course. A survey was administered to the participants to reveal certain social and economic effects of getting prepared for the examination. The data gathered in interview sessions were utilized to provide a crystal clear portrait of the prospective teachers’ experiences about the examination.Findings and Results: The results revealed that The Selection Examination for Professional Posts in Public Organizations (SEPPPO) exerts negative and harmful effects not only on these student-teachers but also on educational faculties and families.Conclusions and Recommendations: The present study suggests that SEPPPO has serious and negative effects on teacher candidates, on families who financially support them and finally on teacher education programs. The greatest limitation of the examination seems to be the validity since it does not assess any competences critical for English teachers. Necessary measures should be taken so as to modify the examination with the goal of exerting a positive washback effect.