Purpose: This study attempts to describe mentors' perceptions of their ethical dilemmas, the derived mentor roles, and the ethical guidelines suggested by mentors, with reference to previous studies exploring the mentors' multifaceted roles. Design/methodology/approach: A total of 60 mentors participated in a two-phase study: the mentors were asked to submit descriptions of their ethical dilemmas to the study web site, and submissions were then discussed in focus groups. A four-stage coding process derived from grounded theory was utilized. Findings: The findings were grouped by means of the ATLAS.ti 5.0 into five main categories: discretion, caring, accountability, autonomy, and distributive justice. The findings raise three important issues: first, mentors perceive their role mainly as empowering their mentees and perceive their powerlessness as being due to lack of tools for dealing with ethical dilemmas. Second, most mentors' ethical dilemmas involved conflicts with school principals. Third, a large number of mentor roles and several of the derived ethical guidelines are unique to the mentoring situation. Practical implications: The findings may promote the design of an educational program for mentors that will relate to the ethical aspects of mentoring. Such programs call for the participation of school principals in program development and meetings to help mentors deal with their ethical dilemmas. Originality/value: While previous studies in mentoring focused on defining mentoring, describing mentors' roles, and suggesting how to build effective mentoring, no study focused on the ethical aspects of mentoring. This study describes mentors' ethical dilemmas, and the unique ethical guidelines that emerged. (Contains 2 tables.)