Background A medical research supervisor is of crucial importance to the undergraduate student enrolled in a research methodology course. A solid relationship between the two is vital to the success of the research project and the overall well-being of the student. The structure of the relationship between a student and a research supervisor is seldom discussed in the context of undergraduate medical research. This study evaluates students’ expectations of their research contributions and their supervisors’ roles. Methods This was an observational study in a large health university in Saudi Arabia. A total of 320 medical students enrolled in a two-year medical research program completed an online survey, of a previously validated instrument, that is, Role Perceptions Rating Scale. Demographic questions such as the current level in the research program (junior or senior) were added. Results The results showed that most students expected the responsibility to be equally shared between the supervisor and student during the development and execution of the research project. Additionally, students expected the research supervisor to be responsible for the research themes and contents, ensuring access to facilities, and assisting in the actual writing of the final research manuscript. Furthermore, the results indicated differences in expectations between junior and senior students. Conclusion This study demonstrates that medical students expect their research supervisors to support them to a significant extent. Understanding medical students’ expectations in a supervisor–student relationship is essential to successful research and collaboration. The evidence gathered in this study has practical implications for educational institutes to base their research training program on these insights. Providing clarity on the expectations and responsibilities of those participating in the research program is crucial, as this would, in turn likely advance the output of the research program and encourage clinicians to join the program as research supervisors.