The aim of this study is to describe student teachers' experiences of their mentors' ethical decisions during their teaching practice sessions for teacher education. The data was gathered from 201 prospective class and subject teachers who described from an ethical viewpoint both positive and negative mentoring experiences. The data analysis is mainly quantitative in nature. According to the results, an ethically successful mentor gives feedback, is student-centered, is fair and just, gives advice, gives enough support and listens carefully, is both flexible and demanding, and is a positive person. An ethically unsuccessful mentor is authoritative, refuses to give feedback, treats student teachers disrespectfully, is hard and critical, interrupts lessons with insufficient reason, discusses delicate and private issues with outsiders, and neglects certain basic tasks. These main findings are significantly supported by previous investigations. (Contains 2 tables.)