The aim of this study is to compare the role of the tutor in an online and a face-to-face problem-based learning (PBL) session to shed light on potential differences of the tutor role in both settings. In this practice-based study we compared the two groups with the same tutor undertaking the same module. Students completed questionnaires about tutor performance, student characteristics and the module. Marks on the end-of-module test were analysed. The tutor was interviewed about his expectations and experiences. One session of each group was recorded and analysed qualitatively. Results show tutor tasks appeared to be comparable in both settings with regard to "content and pedagogical content knowledge," "group dynamics," "process instruction" and "intermediary between faculty and students." The face-to-face group rated tutor performance lower than the online students. Students and tutor identified the absence of nonverbal cues as a limitation of online PBL. In online sessions the tutor additionally provided technical support and moderated the chat box. It is recommended to involve an extra person in online sessions who is responsible for technical issues. This person could also check the chat box for messages of students. Future research should focus on the necessity of an extra tutor training for online sessions.