Abstract Background Preventing mental health problems and promoting mental wellbeing is the aim of school-based mental health literacy (MHL) programs. Previous research suggests that good MHL (knowledge and skills regarding mental health, resilience, and help-seeking) helps people to take good care of their own and others’ mental health and use support-services. In this context the MHL of teachers is highly relevant, as they act as role models and interact with affected pupils on a regular basis, for which certain knowledge and skills are necessary. In this study, we therefore seek to investigate the level of MHL in German high-school teachers as well as their exposure to impaired students and their desire for further education on pupils’ mental health. Methods The data are collected as part of an effectiveness study of a school-based intervention to strengthen MHL (BEWARE), which was developed by our working group. We collect data from teachers who are involved in BEWARE as coaches as well as from those not directly involved (n ≈ 300). Data collection takes place online at three measurement timepoints (6 months apart each). For the analysis presented here, data of the first measurement timepoint with respect to MHL, skills in handling affected students and wishes for additional education on pupils’ mental health are included. Results As the data collection is still ongoing, statistical analyses are not yet completed. We will present data on the current state of knowledge on MHL in German teachers as well as their abilities to deal with affected pupils and their wish for further education. In addition, we will relate the number of affected pupils they teach to depict the relevance in their daily life at school to the above-mentioned measures. Conclusions The acquired data and respective analyses will give us important insights about the objective and subjective need of MHL training in schoolteachers (based on assessed knowledge and their reported wish of additional education). Key messages • Our study will give us important insights about the objective need of MHL training in high-school teachers based on assessed knowledge. • Our results will depict which formats of training teachers would prefer for additional education on pupils’ mental health, which will be a valuable basis for the development of future programs.