Purpose: The purpose of this study is to describe the perceptions of participants regarding a blended learning training course in Chile (and its e-learning adaptation due to the COVID-19 pandemic) for mentor teachers (MTs). The MT learns theoretical elements of mentoring and in parallel accompanies a newly qualified teacher while receiving support from an online tutor. Opinions are presented from MTs and accompanied teachers (ATs) about the contribution, format and methodology of the course. Design/methodology/approach: A program evaluation with mixed methodology was used. Online questionnaires were sent to MTs and ATs at the end of the course. Returned questionnaires totaled 98 MTs and 20 ATs for the blended learning version and 75 MTs and 54 ATs for the e-learning format. In addition, 11 post-course interviews were conducted in three schools with MTs, ATs and their school leaders. Findings: The course contributed to the development of mentoring skills. Participants highlighted the importance of the face-to-face component of both versions. The theoretical-practical methodology used was positively evaluated. Support and feedback provided to MTs by the online tutor was important for developing skills. Research limitations/implications: Results are part of a case (n = 247), so general statements cannot be made about the population. Practical implications: While this program evaluation focuses on a specific context, the results can contribute to the design of effective MT online training courses in other contexts and countries, given the limited body of research on this type of experience. Originality/value: The course provided is described in detail, which may be useful when designing similar mentor education courses in other contexts.